Deck 1: A Modern View of the Universe

Question 1

One light- hour is the distance light travels in one hour. The speed of light is about 300,000 km/s (3 × 105 km/s). How far is 1 light- hour?

A)9)46 trillion km (9,460,000,000,000, or 9.46 × 1012 km)
B)1)08 billion km (1,080,000,000, or 1.08 ×109 km)
C)18 million km (18,000,000, or 1.8 × 107 km)
D)300 thousand km (300,000, or 3 × 105 km)

Answer 1

B

Question 2

A television advertisement claiming that a product is light- years ahead of its time does not make sense because .

A)light- years can only be used to talk about light
B)it uses "light- years" to talk about time, but a light- year is a unit of distance
C)a light- year is an astronomically large unit, so a product could not possibly be so advanced
D)it doesn't specify the number of light- years

Answer 2

B

Question 3

On the scale of the cosmic calendar, in which the history of the universe is compressed to 1 year, how long has human civilization (i.e., since ancient Egypt)existed?

A)a few seconds
B)less than a millionth of a second
C)about half the year
D)a few hours
E)about a month

Answer 3

A

Question 4

What is the diameter of the galaxy, in km?

A)about 1 million trillion km (1018 km)
B)about 1 billion trillion km (1021 km)
C)about 10 trillion km (1013 km)
D)about 100,000 km (105 km)

Question 5

An astronomical unit (AU)is .

A)the current distance between Earth and the Sun
B)the average distance between Earth and the Sun
C)any very large unit, such as a light- year
D)the average distance between any planet and the Sun

Question 6

Which of the following is not a general difference between a planet and a star?

A)Planets are smaller than stars.
B)Planets orbit stars, while stars orbit the center of the galaxy.
C)All planets are made of rock, and all stars are made of gas.
D)Planets are dimmer than stars.

Question 7

The farthest bright galaxies that modern telescopes are capable of seeing are up to

A)10 billion light years away.
B)10 million light years away.
C)1 trillion light years away.
D)1 million light years away.
E)1 billion light years away.

Question 8

Rank the following 4 items by how long it takes for light to reach us from these objects, from shortest to longest.

A)the Andromeda Galaxy, the center of the Milky Way, Pluto, Sun
B)Pluto, Sun, center of Milky Way, the Andromeda Galaxy
C)Pluto, Sun, the Andromeda Galaxy, center of the Milky Way
D)Sun, Pluto, the Andromeda Galaxy, center of the Milky Way
E)Sun, Pluto, center of the Milky Way, the Andromeda Galaxy

Question 9

Astronomers infer that the universe is expanding because distant galaxies all appear to .

A)be moving away from us, with more distant ones moving faster
B)rotate rapidly
C)be made mostly of dark matter
D)be growing in size

Question 10

The term observable universe refers to .

A)the portion of the universe that can be seen by the naked eye
B)the portion of the universe that is not hidden from view by, for example, being below the horizon
C)that portion of the universe that we can see in principle, given the current age of the universe
D)that portion of the universe that we have so far photographed through telescopes

Question 11

The number of stars in the Milky Way Galaxy is approximately .

A)a few hundred billion
B)a few hundred million
C)a few hundred
D)a few hundred thousand

Question 12

Earth is made mostly of metals and rocks. Where did this material come from?

A)It was made by nuclear fission of uranium and other radioactive materials.
B)It was produced by nuclear fusion in stars.
C)It was made by our Sun.
D)It was produced in the Big Bang.
E)It was created by chemical reactions in interstellar space.

Question 13

How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?

A)Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.
B)Earth's rotation carries most people around the axis at about the speed at which the Space Shuttle orbits Earth, and Earth's orbit carries us around the Sun at nearly the speed of light.
C)Earth's rotation carries most people around the axis at about the speed of a commercial jet, and Earth's orbit carries us around the Sun at about the speed of a military jet.
D)Earth's rotation carries most people around the axis at about the speed of a car on the freeway, and Earth's orbit carries us around the Sun at about the speed of a commercial jet.

Question 14

Relative to the age of the universe, how old is our solar system?

A)It is about one- third the age of the universe.
B)It is nearly the same age as the universe.
C)It is between about 5% and 10% as old as the universe.
D)It is about 1% as old as the universe.

Question 15

From the fact that virtually every galaxy is moving away from us and more distant galaxies are moving away from us at a faster rate than closer ones, we conclude that

A)the farthest galaxies will eventually be moving faster than the speed of light.
B)the universe is shrinking.
C)the universe is expanding.
D)the Milky Way Galaxy is expanding.
E)we are located at the center of the universe.

Question 16

One light- year is the distance light travels in one year. The speed of light is about 300,000 km/s (3 × 105 km/s). How far is 1 light- year?

A)18 million km (18,000,000, or 1.8 × 107 km)
B)9)46 trillion km (9,460,000,000,000, or 9.46 × 1012 km)
C)1)08 billion km (1,080,000,000, or 1.08 × 109 km)
D)300 thousand km (300,000, or 3 × 105 km)

Question 17

Suppose we imagine the Sun to be about the size of a grapefruit (about 10 cm across). Which of the following describes the size and distance of Earth on the same scale?

A)Earth is the size of a golf ball about 15 meters away from the Sun.
B)Earth is the size of a golf ball about 1 meter away from the Sun.
C)Earth is the size of a marble about 25 miles away from the Sun.
D)Earth is the size of a point about 15 meters away from the Sun.
E)Earth is the size of a point about 1 meter away from the Sun.

Question 18

Suppose we imagine the Sun to be about the size of a grapefruit. How big an area would the orbits of the eight planets of the Solar System cover?

A)the size of a typical campus building
B)the size of a typical campus
C)the size of a typical dorm room
D)the size of a western state (e.g., Colorado)
E)the size of a small city

Question 19

On the 1- to- 10- billion scale, about how far is it to the nearest stars besides the Sun?

A)400 kilometers
B)4,400 kilometers
C)1,000 kilometers
D)10,000 kilometers
E)4 kilometers

Question 20

If we use 1 millimeter to represent 1 light- year, how large in diameter is the Milky Way Galaxy?

A)1 million millimeters
B)100 millimeters
C)100 kilometers
D)100 meters
E)1 kilometer

Question 21

Which of the following correctly describes the concept of galactic recycling?

A)In the formation of a star, no matter is wasted as all excess material ends up recycled into planets.
B)Stars near the center of the Milky Way are continually recycled to the outskirts of the disk by their orbital motion.
C)New stars are continuously being formed in the Milky Way out of gas that has been ejected from a previous generation of stars.
D)New galaxies are continuously being formed out of gas ejected from a previous generation of galaxies.
E)Life is continuously being spread from star to star in the Milky Way.

Question 22

What do astronomers mean by the Big Bang?

A)the event that marked the birth of our solar system
B)the explosion of a massive star at the end of its life
C)the event that marked the beginning of the expansion of the universe
D)a gigantic explosion that blew all the galaxies in the universe to smithereens

Question 23

A typical galaxy is a .

A)collection of a few hundred million to a trillion or more stars, bound together by gravity
B)relatively small, icy object orbiting a star
C)large, glowing ball of gas powered by nuclear energy
D)system consisting of one or a few stars orbited by planets, moons, and smaller objects
E)nearby object orbiting a planet

Question 24

In a ten- billion to one scale model, the Sun and the Earth are about the size of

A)a grape and a grain of sand.
B)a grapefruit and a grape.
C)a grapefruit and a grain of sand.
D)a basketball and a grape.

Question 25

According to current scientific estimates, when did the Big Bang occur?

A)about 4.5 billion years ago
B)about 65 million years ago
C)about 10 billion years ago
D)about 20 billion years ago
E)about 14 billion years ago

Question 26

Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?

A)The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.
B)The planets range in size from about the size of a marble to the size of a baseball. They are spread out over a region about the size of a football field.
C)The planets are all much smaller than the Sun and are spread out evenly over a distance about the length of a large classroom.
D)The planets are all much smaller than the Sun. Four planets are located within a few centimeters of the Sun, and four planets are located at distances ranging up to about a meter.

Question 27

Stars nearby to our sun have an average relative speed of about 70,000 km/hour. How fast is that in km/s?

A)about 1200 km/s
B)about 4.2 million km/s
C)about 20 km/s
D)about 3000 km/s

Question 28

Where is our solar system located within the Milky Way Galaxy?

A)roughly halfway between the center and the edge of the visible disk of the galaxy
B)very near the center of the galaxy
C)at the far edge of the galaxy's visible disk
D)in the halo of the galaxy

Question 29

How long does it take the Earth to complete one orbit around the Sun?

A)one day
B)one year
C)one month
D)one week
E)The time it takes Earth to orbit the Sun changes significantly from one orbit to the next.

Question 30

Our solar system consists of .

A)the Sun and all the objects that orbit it
B)a few hundred billion stars, bound together by gravity
C)the Sun and the planets, and nothing else
D)the Sun and several nearby stars, as well as the planets and other objects that orbit these stars

Question 31

One of the main reasons the Hubble Space Telescope was built and launched was to measure how fast the universe is expanding. If the expansion turns out to be faster than we thought, our estimate for the age of the universe will be

A)younger (less time between now and the Big Bang).
B)unaffected.
C)older (more time between now and the Big Bang).

Question 32

One light- minute is the distance light travels in one minute. The speed of light is about 300,000 km/s (3×105 km/s). How far is one light- minute?

A)300 thousand km (300,000, or 3 × 105 km)
B)9)46 trillion km (9,460,000,000,000, or 9.46 × 1012 km)
C)1)08 billion km (1,080,000,000, or 1.08 × 109 km)
D)18 million km (18,000,000, or 1.8 × 107 km)

Question 33

Place the following items in order of actual physical size, from smallest to largest.

A)planet, star, galaxy, solar system
B)star, planet, solar system, galaxy
C)planets and stars are about the same size, solar system, galaxy
D)star, planet, galaxy, solar system
E)planet, star, solar system, galaxy

Question 34

Which of the following has your "cosmic address" in the correct order?

A)you, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe
B)you, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe
C)you, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe
D)you, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe
E)you, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

Question 35

One of the most fundamental discoveries about the universe has been that it is expanding. "The universe is expanding" means

A)our estimate for the size of the universe has increased over the last century.
B)galaxies are growing with time.
C)distances between most galaxies are getting larger.
D)the cosmological horizon is growing with time.

Question 36

The total number of stars in the observable universe is about _.

A)the same as the number of grains of sand in a school sandbox
B)100 billion
C)the same as the number of atoms that make up the Earth
D)the same as the number of grains of sand on all the beaches on Earth

Question 37

One light- minute is the distance light travels in one minute. The speed of light is about 300,000 km/s (3 × 105 km/s). How far is 5 light- minutes?

A)5)4 billion km (5,400,000,000, or 5.4 × 109 km)
B)1)5 million km (1,500,000, or 1.5 × 106 km)
C)90 million km (90,000,000, or 9 × 107 km)
D)47.3 trillion km (47,300,000,000,000, or 4.73 × 1013 km)

Question 38

Which of the following best describes the Milky Way Galaxy?

A)a spherically shaped collection of stars including our solar system and about a dozen other solar systems, stretching about 4 light- years in diameter
B)a spiral galaxy with a disk about a billion kilometers in diameter and containing between 100 million and 1 billion stars
C)a spiral galaxy with a disk about 100,000 light- years in diameter and containing between 100 billion and 1 trillion stars
D)a spherically shaped collection of about 1 million stars that is about 100 light- years in diameter
E)a spiral galaxy with a disk about 100,000 light- years in diameter and containing about 100,000 stars

Question 39

Which of the following correctly lists speeds from slowest to fastest?

A)Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, typical speeds of stars in the local solar neighborhood relative to us, the speeds of very distant galaxies relative to us
B)the speed of our solar system orbiting the center of the Milky Way Galaxy, Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us
C)Earth's speed of rotation on its axis, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of revolution about the Sun, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us
D)Earth's speed of revolution about the Sun, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us
E)the speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, Earth's speed of revolution about the Sun, the speed of our solar system orbiting the center of the Milky Way Galaxy

Question 40

Which of the following is smallest?

A)1 AU
B)size of a typical planet
C)1 light- second
D)size of a typical star

Question 41

Which of the following statements about the Milky Way Galaxy is not true?

A)The galaxy is about 100,000 light- years in diameter.
B)One rotation of the galaxy takes about 200 million years.
C)It contains between 100 billion and 1 trillion stars.
D)Our solar system is located very close to the center of the Milky Way Galaxy.

Question 42

On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did Kepler and Galileo first discover that we live on a planet in a solar system?

A)1 week ago
B)December 30
C)1 day ago
D)December 25
E)1 second ago

Question 43

The planet Neptune is, on average, about 4.5 billion km from the sun. How long does it take light from the sun to reach Neptune? (Recall that the speed of light is about 300,000 km/s)

A)about 4 days
B)about 4 minutes
C)about 4 seconds
D)about 4 hours

Question 44

How long does it take our solar system to complete one orbit around the Milky Way Galaxy?

A)100 million years
B)10 thousand years
C)230 million years
D)230 thousand years
E)1 million years

Question 45

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case, .

A)Galaxy 1 must be twice as big as Galaxy 2
B)Galaxy 2 must be twice as old as Galaxy 1
C)we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2
D)we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

Question 46

Suppose we look at a photograph of many galaxies. Assuming that all galaxies formed at the same time after the Big Bang, which galaxy appears to us as the youngest?

A)the galaxy that is furthest from us
B)the galaxy that appears bluest to us
C)the galaxy that appears largest to us
D)the galaxy that is closest to us
E)All galaxies would appear to have the same age.

Question 47

What is the ecliptic plane?

A)the plane of the Milky Way Galaxy
B)the plane of Earth's orbit around the Sun
C)the plane of Earth's equator
D)the plane of the Sun's equator

Question 48

On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is _ .

A)small enough to fit within your hand
B)about 1 meter
C)about 30 meters
D)about 5 meters

Question 49

Which of the following statements does not use the term light- year in an appropriate way?

A)The Milky Way Galaxy is about 100,000 light- years in diameter.
B)A light- year is about 10 trillion kilometers.
C)It will take the Voyager spacecraft about 20,000 years to travel just 1 light- year.
D)It will take me light- years to complete this homework assignment.
E)It's about 4 light- years from here to Alpha Centauri.

Question 50

What is the Sun mainly made of?

A)hydrogen and oxygen
B)nearly equal portions of all the elements
C)carbon and nitrogen
D)oxygen and carbon
E)hydrogen and helium

Question 51

Jupiter is about 5 AU from the Sun. In a ten billion to one scale model, Jupiter is

A)less than one meter from the Sun.
B)about 15 meters from the Sun.
C)about 75 meters from the Sun.
D)about a kilometer from the Sun.

Question 52

Which object has aged the most since it emitted the light we see today?

A)a star near the center of the Milky Way
B)Pluto
C)a star in the Andromeda Galaxy
D)the Sun

Question 53

What is nuclear fusion?

A)the process of combining lightweight nuclei to make heavier nuclei
B)an explosion caused by putting together two volatile chemicals
C)the process of splitting nuclei to produce energy
D)a process that only occurs in bombs
E)the process of turning matter into pure energy

Question 54

Our textbook discusses the cosmic calendar, a model of the history of the universe scaled to a single year. The length of time represented by one month on this cosmic calendar is therefore

A)about one million years.
B)about ten billion years.
C)about ten million years.
D)about 1000 years.
E)about one billion years.

Question 55

When we look at an object that is 1,000 light- years away, we see it .

A)as it is right now, but it appears 1,000 times dimmer
B)as it was 1,000 years ago
C)looking just the same as our ancestors would have seen it 1,000 years ago
D)as it was 1,000 light- years ago

Question 56

What do we mean when we say that the universe is expanding?

A)Within galaxies, average distances between star systems are increasing with time.
B)Everything in the universe is gradually growing in size.
C)The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing.
D)Average distances between galaxies are increasing with time.

Question 57

On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct?

A)in late November
B)in late September
C)in late December
D)in late August
E)in late October

Question 58

Suppose we imagine the Sun to be about the size of a grapefruit (about 10 cm across). How far away are the nearest stars (the three stars of Alpha Centauri)?

A)2)5 miles
B)2,500 miles
C)25,000 miles
D)250 miles
E)the length of a football field

Question 59

The Earth has a radius of about 6,000 km. How long would it take for an object traveling at the speed of light to circle the earth? (Recall that the speed of light is 300,000 km/s)

A)1/50 of a second (0.02s)
B)1/300,000 of a second (0.0000033 s)
C)1/ 6000 of a second (0.00015 s)
D)1/2 of a second (0.5 s)

Question 60

You have taken a picture of a galaxy 1 billion light years away. That picture shows

A)a galaxy that is 1 billion light years old.
B)a galaxy that is 1 billion years old.
C)a galaxy that is 13 billion years old.
D)a galaxy as it was 1 billion years ago.

Question 61

How many seconds are in one year? (Calculate this, do not look it up.)

A)about 30 million (30,000,000, or 3 × 107)
B)about 380 million (380,000,000, or 3.8 × 108)
C)about 3,600 (3.6 × 103)
D)about 86 thousand (86,000, or 8.6 × 105)

Question 62

Approximately how fast is a person located at the Earth's equator traveling due to the rotation of the Earth?

A)17,000 km/hr
B)17 km/hr
C)1,700 km/hr
D)170 km/hr
E)not moving at all

Question 63

Most of the mass in the Milky Way Galaxy is located

A)in the stars in the spiral arms.
B)in the halo (above/below the disk).
C)in the central bulge of the galaxy.
D)within the disk.
E)in the gas and dust.

Question 64

How do scientists estimate how old the universe is?

A)They measure the speeds and distances of galaxies, and calculate the time it took for them to travel that distance.
B)They measure the abundances of radioactive elements in meteorites, and use their half- lives to calculate the age.
C)They look up the answer in a book.
D)They measure how fast the Sun is losing energy, and how much energy it has to lose.
E)They make a guess; no one really knows how old the universe is.

Question 65

The speed of light is about 300,000 km/s (3 × 105 km/s). How far does light travel in 30 seconds?

A)900 thousand km (900,000, or 9 × 105 km)
B)9 million km (9,000,000, or 9 × 106 km)
C)10 thousand km (10,000, or 106 km)
D)300 thousand km (300,000, or 3 × 105 km)

Question 66

Using the ideas discussed in your textbook, in what sense are we "star stuff"?

A)Movie stars and other people are all made of the same stuff, so we all have the potential to be famous.
B)Nearly every atom from which we are made was once inside of a star.
C)The overall chemical composition of our bodies is about the same as that of stars.
D)We could not survive without light from our star, the Sun.

Question 67

One light- hour is the distance that light travels in an hour. How far is this, in kilometers? (Recall that the speed of light is 300,000 km/s.)

A)9)46 trillion km
B)18 million km
C)300,000 km
D)100 million km
E)1)08 billion km

Question 68

Light travels at 300,000 km/sec. About how far does light travel in 10 years?

A)about 10 trillion kilometers
B)about 30 million seconds
C)about 3,000,000 kilometers
D)about 10 light- years
E)about 30,000 kilometers

Question 69

Why do the patterns of the stars in our sky look the same from year to year?

A)because the stars in the constellations move so slowly- typically about the speed of a snail- that their motions are not noticeable
B)because the stars in the constellations are not moving
C)because the stars in the constellations are so far away
D)because the stars in the constellations all move at the same speeds and in the same directions, so they don't change their relative positions

Question 70

Which statement correctly locates the formation of the Earth and the appearance of the first humans on the cosmic calendar, which compresses the 14- billion year history of the universe into one "year," where "now" is exactly midnight, Dec 31?

A)Earth forms in early September, life begins in November, and humans appear on Dec 15.
B)Earth forms in early September, life begins in late September, humans appear a few hours before midnight, Dec 31.
C)Earth forms in January, life begins in April, and humans appear in early December.
D)Earth forms in January, life begins in September, and humans appear in October.

Question 71

On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun?

A)about the distance across the state of Delaware
B)about the distance across 50 football fields
C)100 meters
D)about the distance across the United States

Question 72

How are galaxies important to our existence?

A)Without galaxies, there could not have been a Big Bang.
B)Deep in their centers, galaxies created the elements from which we are made.
C)Without galaxies, the universe could not be expanding.
D)Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

Question 73

Which of the following best describes what we mean by the universe?

A)a vast collection of stars that number as many as the grains of sand on all the beaches on Earth
B)The universe is another name for our Milky Way Galaxy.
C)the sum total of all matter and energy
D)all the galaxies in all the superclusters

Question 74

Wendy measures a recession velocity for two distant galaxies, well outside our Local Group of galaxies. Galaxy A has a recession velocity of 35,000 km/s and Galaxy B has a recession velocity of 70,000 km/s. What can she say about the distances to those galaxies?

A)She can't say anything about the distances to Galaxy A or B.
B)Galaxy B is twice as far as Galaxy A.
C)Galaxy B is four times as far as Galaxy A.
D)Galaxy A is four times as far as Galaxy B.
E)Galaxy A is twice as far as Galaxy B.

Question 75

Which statement about motion in the universe is not true?

A)Your speed of rotation around Earth's axis is faster if you live near the equator than if you live near the North Pole.
B)The mysterious dark matter is the fastest- moving material in the universe.
C)Some stars in the Milky Way Galaxy are moving toward us and others are moving away from us.
D)Except for a few nearby galaxies, all other galaxies are moving away from us.

Question 76

Which of the following is largest?

A)1 light- year
B)size of Pluto's orbit
C)distance to the nearest star (other than our Sun)
D)size of a typical galaxy

Question 77

Rank the following 3 items from nearest to farthest. Hint: the Orion Nebula is a cloud of gas in which young stars are being born within the Milky Way, about 1,500 light- years away.

A)Alpha Centauri, Orion Nebula, star in the center of the Milky Way
B)star in the center of the Milky Way, Alpha Centauri, Orion Nebula
C)star in the center of the Milky Way, Orion Nebula, Alpha Centauri

Question 78

Based on observations of the universal expansion, the age of the universe is about _ .

A)14 trillion years
B)14,000 years
C)14 million years
D)14 billion years

Question 79

How many galaxies are there in the observable universe?

A)infinity
B)roughly (within a factor of 10)the same as the number of stars in our galaxy
C)about as many as the number of grains of sand on all the beaches on Earth
D)about as many as the number of stars we see in the sky with our naked eyes
E)roughly a thousand times more than the number of stars in our galaxy

Question 80

If we imagine the history of the universe compressed into one year, dinosaurs became extinct .

A)about an hour ago
B)yesterday morning
C)about 3 weeks ago
D)about 6 months ago