Moe Has a Big Exam Tomorrow

Moe has a big exam tomorrow. He considered studying this evening, but decided to go out with Curly instead. Since Moe always chooses rationally, it must be true that:

A) the opportunity cost of studying tonight is less than the value Moe gets from spending time with Curly.
B) the opportunity cost of studying tonight is equal to the value Moe gets from spending time with Curly minus the cost of earning a low grade on the exam.
C) Moe gets more benefit from spending time with Curly than from studying.
D) Moe gets less benefit from spending time with Curly than from studying.