Which of the Following Statements About the Per Se Rule

Which of the following statements about the per se rule and the rule of reason antitrust doctrines is true?

A) under rule of reason, only proof of an antitrust violation is needed for the courts to rule the firm violates antitrust laws
B) under per se, the court rule that a certain business practice being committed is automatically illegal
C) under rule of reason, the court consider the impact of a business practice to determine if it is harmful to competition
D) under per se, if precedent found a business action to be illegal, it always remains illegal
E) none of the other choices