This is a weaken question. The President's claim is that switching to an online process caused a decline in sales because customers were unable to work with the online process. The VP's response counters that the decline is industry-wide, and thus not attributable to specifics of their own company. We're looking for a reason why the President's claim may be correct. Consider each choice in turn:

(A) This choice directly strengthens the VP's response by making the industry-wide decline even more specific to Broad Street.
(B) The advantages o the online process are irrelevant, as the apparent problem with it is customers' inability to work with it.
(C) Broad Street's reputation is irrelevant, as the dispute is whether a sales decrease was caused by a switch to an online order process or a widespread decline in sales.
(D) This is correct. It points out something typically associated with the VP's claim, and shows that something different occurred. Further, what actually happened--one-quarter of customers not ordering--is consistent with the President's argument.
(E) Whether some of Broad Street's competition did the same thing that Broad Street did does not tell us whether an industry-wide decline was responsible for Broad Street's lagging sales.