Which One of the Following Students Is Displaying Intrinsic Motivation

Which one of the following students is displaying intrinsic motivation?

A) Alison loves to play the viola and so she practices for at least an hour every day.
B) Heinz works hard in his classes because his parents have promised to buy him a car if he gets at least a 3.5 grade-point-average this year.
C) Jasmin does her math homework faithfully every night because she likes her teacher and wants to please him.
D) Graham takes physics because he wants to become an engineer and make a lot of money.