What Must a Plaintiff Prove to Show a Per Se

What must a plaintiff prove to show a per se violation of the Sherman Act?

A) That the prohibited conduct occurred.
B) That the prohibited conduct occurred and the proper amount of economic harm.
C) That there is an unambiguous presumption of unfair trust activity.
D) That trust activity is likely to dilute efficiency among the competition.
E) An amount of economic harm meeting standards set by the Sherman Act itself.