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 pretzels each month?

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