Which of the Following Examples About Intrinsic Motivation Is Correct

Which of the following examples about intrinsic motivation is correct?

A) You are working hard on a task because you know it will lead to a high grade.
B) You are working hard on a task because you think it is interesting.
C) You keep working on a task, even when you think it is boring.
D) You decide not to work hard on a competition with a cash prize, because you know that other people need the money more than you do.