Lunch in Jamie's Dorm Is an All-You-Can-Eat Buffet, Served from 11

Lunch in Jamie's dorm is an all-you-can-eat buffet, served from 11 a.m. until 1 p.m. By noon, the buffet is picked over, and by 12:30, there are very few popular items left. The garbage bins, though, are full of food. The buffet in Jamie's dorm is an example of:

A) an efficient subsidy.
B) the tragedy of the commons.
C) excess supply in the market.
D) a good with positive externalities.