Traci Consumes Two Goods,lemonade and Pretzels

Multiple Choice

Traci consumes two goods,lemonade and pretzels.Lemonade costs $1 per glass,and she consumes it to the point where the marginal utility she receives from her last glass of lemonade is 3.Pretzels cost $2 per bag.The relationship between the marginal utility Traci gets from eating a bag of pretzels and the number of bags she eats per month is as follows: If Traci is maximizing his utility,how much does she spend on potato chips each month?

A) $2
B) $6
C) $8
D) $12