Manager: Our company’s mail-order sales have recently increased 25 percent. ... ...

Which one of the following, if true, most strengthens the manager’s argument?
(A) Mail-order sales have been decreasing for companies that do not offer unlimited free shipping.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in June 2012 LSAT (PT66): Logical Reasoning B