Which of the following is NOT a type of sexual discrimination?

Workplace harassment is, in fact, a recognized form of sexual discrimination. This type of harassment occurs when unwanted sexual advances, requests for sexual favors, or other verbal or physical conduct of a sexual nature creates an intimidating, hostile, or offensive work environment.

The other options represent well-established types of sexual discrimination. Quid pro quo refers specifically to situations where employment decisions are based on an individual's acceptance or rejection of sexual advances. Sexual orientation sex discrimination involves treating someone unfavorably because of their sexual orientation, while gender-based sex discrimination refers to treating someone differently based on their gender. Each of these options clearly falls under the umbrella of sexual discrimination, making workplace harassment the only answer that aligns with the idea of being 'not' a type.