Suppose Darren pays $10 to eat at an All-you-can-eat dessert buffet. He was very hungry, and so he finds the 1st dessert very satisfying. The 2nd dessert is still very good, and the 3rd is just good. By the time he finishes his 4th dessert, he is feeling full. He insists on eating the 5th dessert, and he starts to feel uncomfortable. Which of the following describe(s) his actions?

a. All of the answers are correct

b. Diminishing marginal utility applies to his consuming the five desserts

c. His total utility from consuming four desserts is higher than from consuming five

d. The marginal utility from the 5th dessert is negative