Why Do People Tend to Eat More at All-You-Can-Eat Buffet

Why do people tend to eat more at all-you-can-eat buffet restaurants than at restaurants where each item is purchased separately?

A) Once the all-you-can-eat meal is purchased, consumers view additional trips back to the buffet as having a price of zero.
B) MU/P is consistently greater at all-you-can-eat restaurants.
C) People who eat at all-you-can-eat restaurants do not experience diminishing marginal utility.
D) Food at all-you-can-eat restaurants tends to have fewer calories, so consumers feel the need to consume a greater volume of food.