Traci consumes two goods, lemonade and pretzels. Lemonade costs $2 per glass, and she consumes it to the point where the marginal utility she receives from her last glass of lemonade is 4. Pretzels cost $3 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: Bags of pretzels 1 2 3 4 5 6 Marginal utility 30 20 12 6 2 0 If Traci is maximizing her utility, how many bags of potato chips does she buy each month? a. 3 b. 4 c. 5 d. 6