Which Scenario Is an Example of Sexual Harassment That Creates

Which scenario is an example of sexual harassment that creates a hostile environment?

A) A professor promises a student a passing grade in exchange for a sexual favor.
B) A professor makes a sexual joke while standing outside of the classroom.
C) A professor makes repeated sexual jokes over the course of several class periods.
D) A professor takes his teaching assistants out for lunch as an end-of-term thank you.
E) A professor compliments his teaching assistant's new haircut.