Deck 4: Demand and Supply

Question 1

What is the "quantity demanded"?

A) the amount of a good people desire
B) the amount of a good people are able and willing to buy during a specific time period and at a given price
C) the amount of a good people are able and willing to buy at all possible prices
D) the maximum amount of a good that can be consumed during a specific time period
E) the minimum amount of a good that people are willing to buy during a specific time period and at a given price

Answer 1

the amount of a good people are able and willing to buy during a specific time period and at a given price

Question 2

The "law of demand" refers to the fact that,other things remaining the same,when the price of a good rises,

A) the demand curve shifts rightward.
B) the demand curve shifts leftward.
C) there is a movement down along the demand curve to a larger quantity demanded.
D) there is a movement up along the demand curve to a smaller quantity demanded.
E) the demand curve shifts rightward and there is a movement up along the demand curve to a smaller quantity demanded.

Answer 2

there is a movement up along the demand curve to a smaller quantity demanded.

Question 3

Which of the following statements is true about a competitive market? A competitive market

A) must have a physical location.
B) includes markets for goods and services but not for inputs.
C) has so many buyers and sellers that no one can influence the price.
D) has one seller competing to sell his or her product.
E) has a handful of sellers but always has many buyers.

Answer 3

has so many buyers and sellers that no one can influence the price.

Question 4

A market is defined as

A) a physical place where people buy only goods.
B) a physical place where people buy both goods and services.
C) a store where people buy physical goods.
D) any arrangement that brings buyers and sellers together.
E) a place where one good is bartered for another.

Question 5

A demand schedule shows

A) the quantities that people plan to buy in all possible circumstances.
B) the quantities that people plan to buy at each different price when all other influences on buying plans remain the same.
C) the quantities that people would plan to buy if they could afford them at each different price when all other influences on buying plans remain the same.
D) the quantities that people plan to buy at each different income when all other influences on buying plans remain the same.
E) the quantities that people plan to buy at each different price as long as producers are willing to supply that quantity.

Question 6

EBay

A) will be considered a market when the Internet firms are profitable.
B) is a market because buyers and sellers are brought together to buy and sell.
C) would be a market if there was only one physical location.
D) cannot function as a market.
E) is not a market because buyers can buy from only one seller at any point in time.

Question 7

The "quantity demanded" of any good or service is ________ during a specified time period and at a specified price.

A) the amount people are willing to buy
B) the amount people are able to buy
C) the amount people are willing and able to offer
D) the amount people are willing and able to buy
E) the amount people are willing to buy because it is the amount sellers are willing to sell

Question 8

The price of cotton clothing falls.As a result,

A) the quantity demanded of cotton clothing increases.
B) the demand for cotton clothing increases.
C) the quantity demanded of cotton clothing decreases.
D) the demand for cotton clothing decreases.
E) both the demand for cotton clothing increases and the quantity demand of cotton clothing increases.

Question 9

The law of demand refers to how

A) demand changes when people's incomes change.
B) demand changes when the prices of substitutes and complements change.
C) the quantity demanded changes when the price of the good changes.
D) the price of the good changes when people's demand for the good changes.
E) the quantity demanded changes when the demand for the good changes.

Question 10

The law of demand implies that,other things remaining the same,

A) as the price of a cheeseburger rises, the quantity of cheeseburgers demanded increases.
B) as the price of a cheeseburger rises, the quantity of cheeseburgers demanded decreases.
C) as income increases, the quantity of cheeseburgers demanded increases.
D) as the demand for cheeseburgers increases, the price of a cheeseburger falls.
E) as more people demand cheeseburgers, the quantity demanded increases.

Question 11

A demand curve

A) has an upward slope.
B) has a downward slope.
C) is a graph of the relationship between quantity demanded of a good and its price.
D) Both answers B and C are correct.
E) Both answers A and C are correct.

Question 12

The American Dairy Association starts a highly successful advertising campaign that makes most people want to drink more milk.As a result,

A) the demand for milk increases.
B) the quantity demanded of milk increases.
C) the price of milk falls to encourage people to drink more milk.
D) the demand for milk is not affected.
E) the demand for milk decreases because the price of milk rises.

Question 13

Gasoline prices increase by 50 percent and other things remain the same.As a result,there is

A) an increase in the demand for gasoline.
B) a decrease in the demand for gasoline.
C) no change in the quantity of gasoline demanded.
D) a decrease in the quantity of gasoline demanded.
E) More information is needed to determine if the demand for gasoline increases or decreases.

Question 14

In stores,it is common to find seasonal products marked down when the season ends.What explains this behavior?

A) The law of demand is being used to increase the quantity demanded.
B) The store is trying to increase its customers' demand for the product.
C) The store manager must be trying to drive away customers by selling low quality products.
D) The store is trying to increase its customers' incomes by increasing their purchasing power.
E) The store is trying to sell the goods and realizes that they are substitutes for other goods whose prices have risen.

Question 15

Which of the following is true regarding demand?
i.Demand is the relationship between quantity demanded and the price of a good when all other influences on buying plans remain the same.
ii.Demand refers to one quantity at one time.
iii."Demand" and "quantity demanded" are the same thing.

A) i only
B) ii only
C) both i and ii
D) iii only
E) both ii and iii

Question 16

A demand schedule

A) shows the quantity demanded at one price.
B) is a graph showing a relationship between the quantity demanded and the price of a good.
C) is a list of the quantities demanded at each different price when all other influences on buying plans remain the same.
D) shows that demand is on schedule.
E) shows how the demand changes when the supply changes.

Question 17

Which of the following results in a movement upward along the demand curve for movies?

A) an increase in the price of movie tickets
B) a decrease in the price of movie tickets
C) an increase in income, assuming that movies are a normal good
D) a decrease in income, assuming that movies are a normal good
E) a decrease in the price of NetFlix, a substitute for movies

Question 18

An increase in the quantity demanded is shown as

A) a movement along the demand curve.
B) a movement toward the demand curve.
C) a rightward shift of the demand curve.
D) a leftward shift of the demand curve.
E) both a movement along the demand curve and a shift of the demand curve.

Question 19

The downward slope of a demand curve

A) represents the law of demand.
B) shows that as the price of a good rises, consumers increase the quantity they demand.
C) indicates how the quantity demanded changes when incomes rise and the good is a normal good.
D) indicates how demand changes when incomes rise and the good is a normal good.
E) indicates how demand changes when the price changes and the good is a normal good.

Question 20

Which of the following describes the law of demand? When other things remain the same,as

A) the price of gas falls, the quantity demanded of gas increases.
B) the quantity demanded of bread increases, the price of bread falls.
C) the price of peanut butter increases, the quantity demanded of jelly decreases.
D) your income increases, you'll buy more hamburgers.
E) more people decide to eat pizza, the demand for pizza increases.

Question 21

Consider the market for smart phones.Which of the following shifts the demand curve rightward?

A) an increase in the price of smart phones
B) a decrease in the price of smart phones
C) an increase in the price of land-line phone service, a substitute for smart phones
D) a decrease in the number of smart phone buyers
E) an increase in the supply of smart phones.

Question 22

Which of the following increases the demand for a good or service?

A) a fall in the price of the good or service
B) a smaller number of consumers wanting to buy the good or service
C) a rise in the price of the good or service
D) a rise in the price of a substitute good or service
E) a rise in the price of a complement

Question 23

Which of the following shifts the demand curve for movies rightward?

A) an increase in the price of NetFlix, a substitute for movies
B) an increase in the price of movie tickets
C) a decrease in the price of move tickets
D) an increase in movie star salaries
E) an increase in the price of HDTV sets

Question 24

Market demand curves are obtained by

A) determining the price each consumer is willing to pay for the good and summing those prices across all consumers.
B) observing the prices and quantities sold in a market over time and plotting those price-quantity combinations in a graph.
C) summing the quantities every consumer is willing to buy at each different price.
D) observing the behavior of an individual consumer in a market.
E) averaging the quantities every consumer is willing to buy at each different price.

Question 25

Consumers eat salsa with taco chips.The price of salsa rises.How does the increase in the price of salsa affect the demand for taco chips?

A) It decreases the demand for taco chips.
B) It increases the demand for taco chips.
C) It has no effect on the demand for taco chips.
D) It will decrease the demand for taco chips only if taco chips are a normal good.
E) It could increase, decrease, or have no effect on the demand for taco chips, but more information is needed to determine the impact.

Question 26

There are five hundred buyers in the market for cheese.If we know each individual's demand curves,to find the market demand,we must

A) add the prices that each buyer will pay at every quantity.
B) add the quantities that each buyer will purchase at every price.
C) multiply the price times quantity for each buyer and then add the resulting products together.
D) average the price each buyer is willing to pay for each given quantity.
E) give up because there is no way to find the market demand.

Question 27

If the demand for used cars decreases after the price of a new car falls,used cars and new cars are

A) inferior goods.
B) substitute goods.
C) complementary goods.
D) normal goods.
E) The questions errs because it is the quantity of used cars, NOT the demand for used cars, that will change when the price of a new car falls.

Question 28

The phrase "a change in demand" most directly implies a

A) movement along a demand curve.
B) movement along the price curve.
C) change in the quantity demanded of a good.
D) shift of the demand curve.
E) movement along the quantity curve.

Question 29

The market demand curve

A) cannot show how quantity demanded changes in response to a change in price.
B) cannot show a change in demand for a good.
C) is the horizontal sum of individual demand curves.
D) is the vertical sum of individual demand curves.
E) is upward sloping.

Question 30

When demand increases,

A) consumers are willing to buy more at any price.
B) consumers buy more of the good only if its price falls.
C) the price is lower at any level of quantity demanded.
D) consumers buy more of the good only if its price rises.
E) the demand curve shifts leftward.

Question 31

Two brands of water,Natural Water and Mountain Water,are close substitutes.If the price of Mountain Water decreases,the fall in price

A) shifts the demand curve for Natural Water rightward.
B) shifts the demand curve for Natural Water leftward.
C) increases the price of Natural Water.
D) increases the demand for Mountain Water.
E) More information is needed to determine if the demand curve for Natural Water shifts rightward or leftward.

Question 32

To find the market demand curve for in-line skates,we must

A) add the quantities demanded at every price and every income by every buyer of in-line skates.
B) add the quantities demanded at prices that all buyers can afford to pay.
C) sum horizontally the individual demand curves of all the buyers.
D) take account of the skate buying plans of all actual and potential buyers in all possible situations.
E) None of the above answers is correct because we need also to take account of the supply of in-line skates.

Question 33

A change in the demand for apples could result from any of the following EXCEPT

A) a change in the number of buyers.
B) increased preferences for fresh fruit consumption for health reasons.
C) a change in the price of an apple.
D) a change in the price of a banana.
E) a change in income.

Question 34

Consumers regard Dell computers and Apple computers as substitutes.If the price of a Dell computer decreases,the

A) demand for Dell computers increases.
B) demand for Apple computers increases.
C) demand for Apple computers decreases.
D) supply of Dell computers increases.
E) demand for Dell computers decreases.

Question 35

Which of the following shifts the demand curve for movies leftward?

A) a decrease in the price of NetFlix, a substitute for movies
B) a decrease in the price of movie tickets
C) an increase in the price of movie tickets
D) an increase in movie star salaries
E) an increase in incomes, assuming movies are a normal good

Question 36

Car insurance and cars are complements.If the price of car insurance increases,the

A) demand for cars decreases.
B) demand for cars increases.
C) quantity of cars demanded decreases.
D) quantity of cars demanded increases.
E) More information is needed to determine if the demand increases or decreases.

Question 37

Changes in which of the following factors do NOT shift the demand curve?

A) the price of the good
B) buyers' incomes
C) the price of a substitute good
D) the number of buyers
E) the price expected in the future

Question 38

Demand curves slope ________ because as the price increases and other things remain the same,the quantity demanded ________.

A) downward; decreases
B) downward; increases
C) upward; decreases
D) upward; increases
E) downward; does not change

Question 39

The market demand curve for mangos is

A) the same as the demand curve of one buyer in a market with many buyers.
B) upward sloping because rich people can afford more mangos than poor people can buy.
C) the horizontal sum of the individual demand curves of all the buyers.
D) the vertical sum of the individual demand curves of all the buyers.
E) the horizontal average of the individual demand curves of all the buyers.

Question 40

The market demand curve for mousetraps is

A) found by summing the quantities of mousetraps demanded at each income level by each buyer.
B) found by summing the prices of mousetraps at each quantity of mousetraps demanded by each buyer.
C) the horizontal sum of the individual demand curves for mousetraps of all the buyers.
D) Both answers B and C are correct.
E) Both answers A and C are correct.

Question 41

If macaroni and cheese is an inferior good,then a decrease in income results in

A) an increase in the demand for macaroni and cheese.
B) a decrease in the demand for macaroni and cheese.
C) an increase in the supply of macaroni and cheese.
D) a decrease in the supply of macaroni and cheese.
E) Both answers A and D are correct.

Question 42

Ramen noodles are a staple food item for many college students.Ramen noodles are very inexpensive,easy to prepare,and can be combined easily with other foods.After students graduate,find employment,and earn a higher income,they decrease their Ramen noodle purchases significantly.In this case,Ramen noodles are

A) a normal good.
B) an inferior good.
C) a complement for higher income people.
D) a substitute good.
E) None of the above answers is correct.

Question 43

Scooters and bicycles are substitutes.Suppose that the price of a bicycle falls.Which of the figures above best illustrates how this fall in price affects the demand curve for scooters?

A) Figure A
B) Figure B
C) Figure C
D) Figure D
E) None of the above answers is correct because the change in the price of a bicycle will affect the supply curve not the demand curve.

Question 44

If income increases and the demand for bus rides decreases,

A) bus rides are a normal good.
B) consumers are behaving irrationally.
C) bus rides are an inferior good.
D) bus rides are a substitute good.
E) bus rides must be a complement good with some other good.

Question 45

Scooters are a normal good and buyers' incomes decrease.Which of the figures above best illustrates how this change affects the demand curve for scooters?

A) Figure A
B) Figure B
C) Figure C
D) Figure D
E) None of the above answers is correct because the decrease in income will affect the supply curve not the demand curve.

Question 46

A huge 50 percent off sale on golf clubs is advertised for next week.What happens this week in the market for golf clubs?

A) The supply of golf clubs increases.
B) The supply of golf clubs decreases.
C) The demand for golf clubs increases.
D) The demand for golf clubs decreases.
E) The demand for and the supply of golf clubs decreases.

Question 47

A student at New York University used to take the Redhound bus when she visited her grandmother in Boston.After graduating,although the bus fare and the plane fare were the same as they were when she was a student,with a well-paid job on Wall Street she now takes the plane to Boston to visit her grandmother.For this student,travel by Redhound bus is

A) a normal good.
B) an inferior good.
C) a substitute good.
D) a complement good.
E) a good with negative preferences.

Question 48

Hot dogs and hot dog buns are complements.If the price of a hot dog falls,then

A) the demand for hot dogs will increase.
B) the demand for hot dog buns will decrease.
C) the quantity demanded of hotdogs will decrease.
D) the demand for hot dog buns will increase.
E) the quantity demanded of hot dog buns will increase.

Question 49

Soda and hot dogs are complements for one another.If a shortage of carbonated water leads to an increase in the price of soda,then the

A) demand for hot dogs increases.
B) demand for hot dogs decreases.
C) quantity of hot dogs demanded increases.
D) quantity of hot dogs demanded decreases.
E) More information is needed to determine if the demand increases or decreases.

Question 50

If the demand for digital cameras increases when consumers' incomes rise,then digital cameras are

A) a normal good.
B) an inferior good.
C) a substitute for camcorders.
D) a complement to camcorders.
E) made using advanced technology.

Question 51

What happens to the demand for a good if a complement's price increases?

A) The demand decreases and the demand curve shifts rightward.
B) The demand increases and the demand curve shifts rightward.
C) The demand decreases and the demand curve shifts leftward.
D) The demand increases and the demand curve shifts leftward.
E) There is no impact on demand for the good and the demand curve does not shift.

Question 52

A popular dinner among college students today is sushi,green tea,and wasabi dip so these foods are complements.If the price of green tea increases and the price of wasabi dip increases,what would be the effect on demand for sushi at lunch?

A) The demand for sushi would decrease.
B) The demand for sushi would be unaffected, but the price would increase.
C) The demand for sushi could increase or decrease.
D) The demand for sushi would increase.
E) The demand for sushi would be unaffected, but the price would decrease.

Question 53

You are just about to finish college and are about to start a high paying job.Because of this new job,what is the most likely outcome in the market for cars?

A) Your demand for cars will decrease.
B) The market supply of cars will increase.
C) Your demand for cars will increase.
D) The market supply of cars will decrease.
E) The demand and the supply for cars will decrease.

Question 54

In a recession,consumers have less income to spend.As a result,if dining out is a normal good,then which of the following would happen to the demand curve for dining out?

A) The demand curve would shift leftward.
B) The demand curve would not shift but the price of dining out would rise.
C) The effect on the demand curve is unknown.
D) The demand curve would shift rightward.
E) The demand curve would not shift but the price of dining out would fall.

Question 55

Which of the following increases the demand for a good?

A) a rise in the price of a complement
B) the expectation that future income will be higher
C) an increase in income, assuming the good is an inferior good
D) a decrease in the number of buyers
E) a fall in the price of a substitute

Question 56

Which of the following is true?

A) For an inferior good, when income increases, the demand curve shifts leftward.
B) If the price of a substitute rises, the demand curve shifts leftward.
C) If people expect the price of a good will rise in the future, the demand curve shifts leftward.
D) An increase in population shifts the demand curve leftward.
E) An increase in the cost of producing a good shifts the demand curve leftward.

Question 57

Water bottlers announce that next month the price of bottled water will rise by 25 percent.Which of the following occurs immediately?

A) The quantity of bottled water demanded increases.
B) The quantity of bottled water demanded decreases.
C) The demand for bottled water decreases.
D) The demand for bottled water increases.
E) None of the above answers is correct because it is the supply that immediately changes, not the demand.

Question 58

Suppose that tattoos gained immense popularity with retired people as well as college students.This gain in popularity best reflects which of the following influences on buying plans?

A) the price of a substitute good
B) income
C) expectations
D) preferences
E) the price of a complement good

Question 59

Consider the market for cellular phones.Which of the following shifts the demand curve leftward?

A) studies showing using cellular phones can cause brain cancer
B) a decrease in the price of cellular phones
C) a decrease in the quantity demanded of cellular phones
D) an increase in the services provided by cellular phones, such as text messaging
E) an increase in the price of cellular phones

Question 60

If the demand for a good increases when people's incomes increase,

A) the good is an inferior good.
B) the law of demand is violated.
C) the good's demand curve must be slope upward.
D) the good is a normal good.
E) the good is a substitute good for an inferior good.

Question 61

According to the figure above,which of the following events will increase the quantity demanded of bottled water?

A) a fall in the price of soda
B) a rise in the price of a fitness club membership
C) an increase in the number of buyers of bottled water
D) a fall in the price of bottled water
E) a rise in the price of bottled water

Question 62

The "law of demand" indicates that if the University of Maine increases tuition,all other things remaining the same,

A) the demand for classes will decrease at the University of Maine.
B) the demand for classes will increase at the University of Maine.
C) the quantity of classes demanded will increase at the University of Maine.
D) the quantity of classes demanded will decrease at the University of Maine.
E) both the demand for and the quantity of classes demanded will decrease at the University of Maine.

Question 63

The graph illustrates the demand for peanuts.Peanuts are a normal good because the

A) demand curve for peanuts slopes downward.
B) demand for peanuts increases when income increases.
C) demand for peanuts increases when the price of one of its substitutes rises.
D) peanuts have both substitutes and complements.
E) demand curve shows that if the price of peanuts rises, there is a movement along the demand curve to a lower quantity demanded.

Question 64

A scooter uses much less gasoline than does a car.Suppose the price of gasoline rises substantially.Which of the figures above best illustrates how this change affects the demand curve for scooters?

A) Figure A only
B) Figure B only
C) Figure C only
D) Figure D only
E) Both Figure A and Figure D

Question 65

In the above figure,the shift in the demand curve from D to D₁ can be the result of

A) a decrease in income if pizza is a normal good.
B) a decrease in the price of a sub sandwich, a substitute for pizza.
C) an increase in the price of soda, a complement to pizza.
D) an increase in the number of teenagers, all of whom demand more pizza than do other age groups.
E) new technology that increases the profit from producing pizza.

Question 66

In the above figure,the shift in the demand curve from D to D₂ can be the result of

A) an increase in income if pizza is a normal good.
B) an increase in the price of a sub sandwich, a substitute for pizza.
C) an increase in the price of soda, a complement to pizza.
D) a change in quantity demanded.
E) a decrease in the supply of pizza that raises the price of pizza.

Question 67

In the above figure,the shift in the demand curve from D to D₁ can be the result of

A) an increase in the price of pizza.
B) an increase in the price of a sub sandwich, a substitute for pizza.
C) an increase in the price of soda, a complement to pizza.
D) a change in quantity demanded.
E) a decrease in income if pizza is a normal good.

Question 68

In the above figure,________ will shift in the demand curve from D to D₁.

A) an increase in income if pizza is an inferior good
B) a decrease in the price of a sub sandwich, a substitute for pizza
C) buyers' expectation that pizza will be less expensive next week
D) a scientific article published that demonstrates eating pizza is good for one's health
E) a fall in the cost of producing pizza

Question 69

Other things remaining the same,the quantity of a good or service demanded will increase if the price of the good or service

A) rises.
B) falls.
C) does not change.
D) rises or does not change.
E) rises or falls.

Question 70

People consume more soup as temperatures falls.So,as cold weather approaches,

A) the quantity of soup demanded increases.
B) the demand for soup increases.
C) people move closer to their demand curve for soup.
D) people move farther beyond their demand curves.
E) both the demand and the quantity demanded of soup increase.

Question 71

Over the next few years more and more people prefer to ride on scooters.Which of the figures above best illustrates how this change affects the demand curve for scooters?

A) Figure A
B) Figure B
C) Figure C
D) Figure D
E) None of the above answers is correct because the change in tastes will affect the supply curve not the demand curve.

Question 72

The figure above shows the market for iPods.Which of the following creates a movement from point A to point B?

A) a requirement that all students at universities have an iPod
B) a decrease in the price of iPods
C) a decrease in the price of Zunes, a substitute for iPods
D) an increase in the price of iPods
E) an increase in people's incomes

Question 73

The impact of an increase in the price of a particular good is illustrated as a

A) leftward shift in its demand curve.
B) rightward shift in its demand curve.
C) movement upward and to the left along its demand curve.
D) movement downward and to the right along its demand curve.
E) rightward shift in its demand curve and a movement upward and to the left along its demand curve.

Question 74

The figure above shows the market for iPods.Which of the following shifts the demand curve from D₀ to D₂?

A) a decrease in the price of Zunes, a substitute for iPods
B) an increase in the price of iPods
C) a requirement that all students at universities have an iPod
D) a decrease in the price of iPods
E) a decrease in people's incomes if iPods are a normal good

Question 75

Which of the following brings only an increase in the quantity demanded of a good?

A) a decrease in income, assuming the good is an inferior good
B) a rise in the price of a substitute good
C) a fall in the price of the good itself
D) an expectation that the good's price will rise in the future
E) a decrease in income, assuming the good is a normal good

Question 76

In the above figure,the movement from point a to point b reflects

A) a decrease in the price of pizza.
B) an increase in the demand for pizza.
C) an increase in the number of people who eat pizza.
D) an increase in the price of the tomato sauce used to produce pizza.
E) a decrease in the number of firms producing pizza.

Question 77

Pizza is a normal good.In the above figure,the shift in the demand curve from D to D₂ can be the result of

A) a decrease in the price of soda, a complement to pizza.
B) an increase in the price of hamburgers, a substitute for pizza.
C) a decrease in income.
D) a study that shows that pizza is a very healthy food.
E) an increase in the cost of producing pizza.

Question 78

The figure above shows the market for iPods.Which of the following shifts the demand curve from D₀ to D₁?

A) a decrease in the price of Zunes, a substitute for iPods
B) an increase in the price of iPods
C) a requirement that all students at universities have an iPod
D) a decrease in the price of iPods
E) an increase in people's incomes

Question 79

$$\begin{array} { c c } \begin{array} { c } \text { Price } \\\text { (dollars per latte) }\end{array} & \begin{array} { c } \text { Quantity demanded } \\\text { (lattes per hour) }\end{array} \\\hline 1 & 90 \\2 & 80 \\3 & 60 \\4 & 30 \\\hline\end{array}$$

-The table above gives the demand schedule for lattes at the Bottomless Cup.If the price of a latte is $3,then the quantity of lattes demanded is ________ an hour.

A) 90
B) 30
C) 80
D) 60
E) 230

Question 80

A normal good is defined as a good

A) with a downward sloping demand curve.
B) for which demand increases when the price of a substitute rises.
C) for which demand increases when income increases.
D) for which demand increases when the number of demanders increases.
E) for which demand increases when the price of a complement falls.