Which of the Following Is an Example of Intrinsic Motivation

Which of the following is an example of intrinsic motivation?

A) Paula's mother is going to give her $20 for every A on her report card.
B) Jennifer is going to study hard for her math test because if she does well, she gets to go on a trip to visit friends.
C) Jamie likes to play baseball, so he learns a new pitch for next week's game.
D) Tran goes to law school because a lot of lawyers make big salaries.