A Major Argument Put Forth by Defenders of the Commission

A major argument put forth by defenders of the commission system is that a commission:

A) keeps the agencies from placing advertising in expensive media.
B) ties agency compensation to the inflation in media costs.
C) is very complex to administer.
D) is simple and keeps the emphasis in agency compensation on non-price factors.
E) encourages agencies to use noncommissionable media such as direct mail.