Which of the Following Occurs When a Plaintiff Expressly Agrees,usually

Which of the following occurs when a plaintiff expressly agrees,usually in a written contract,to assume the risk posed by the defendant's behavior?

A) Implied assumption of the risk.
B) Express assumption of the risk.
C) Express assumption of the last-clear-chance doctrine.
D) Implied assumption of the last-clear-chance doctrine.
E) Pure comparative negligence.