Which Is the Most Difficult Part of Establishing the Defense

Which is the most difficult part of establishing the defense of assumption of the risk?

A) Showing that the plaintiff assumed the risk of the actual harm suffered.
B) Showing that the defendant was aware that the plaintiff assumed the risk.
C) Showing that the plaintiff was aware of applicable law.
D) Showing that the plaintiff signed the contract assuming the risk without duress.
E) Showing that the defendant was either contributorily or comparatively negligent (depending on the jurisdiction in which the case is tried) .