Last night, gavan had a wonderful dinner of many courses. in the morning, he is so full that he cannot imagine eating. at his early morning meeting, pastries are available. although the pastries look and smell delicious, gavan is too full to try one. yet a few minutes later, he feels quite hungry. the best explanation for gavan's hunger would come from:

I believe the answer is:  Classical conditioning.

 Classical conditioning happen when an organism acquire a new behavior after biologically potent stimulus is paired with a previously neutral stimulus.
In the example above, Gavan's hunger during the meeting does not come because his body actually need the food, but because it has been conditioned to be filled everytime Gavan see or smell foods.