Which of the Following Would Be an Example of a Contingent

Which of the following would be an example of a contingent worker?

A) authors like Stephen King and Dean Koontz who are able to live off the royalties from their books
B) a plumber who owns his own business, even though he has no employees
C) a stripper who is considered to be an independent contractor and therefore exempt from minimum-wage laws
D) a producer at a news station who is forced to sign a three-year contract
E) university professors who have tenure, making them much harder to fire