All of the Following Statements Regarding the Legal and Regulatory

All of the following statements regarding the legal and regulatory aspects of pricing are true except

A) there has been a movement toward a "rule of reason" in both horizontal and vertical price fixing cases.
B) the Robinson-Patman Act allows for price differentials to different customers under the "cost justification defense."
C) a manufacturer's MSRP has been declared illegal per se by a recent U.S. Supreme Court decision.
D) the "rule of reason" perspective is the direct opposite of the per se rule.
E) wholesalers can fix the maximum retail price for their products provided the price agreement does not create an "unreasonable restraint of trade."