Evaluate argument

[BTGmoderatorRO]

Professor: In an effort to combat stagnating revenues, an apparel company launched a special six-month advertising campaign, purchasing fifty percent of the poster space on the subway trains of ten major cities. The tactic was risky due to the large outlay of funds required, but the results demonstrate that the campaign was a resounding success. During the months of the campaign, sales climbed to record levels, and the company had the number one ranking in market share.
The answer to which of the following would be most useful in evaluating the professor's argument?

(A) What percent of subway riders were aware of the apparel company prior to the campaign?
(B) How profitable was the company during the months of the campaign?
(C) Were revenues throughout the apparel industry stagnant in the months prior to the campaign?
(D) Did any of the company's divisions experience a significant reduction in sales?
(E) At the time of the campaign, did the company significantly increase spending on other forms of marketing?
OA is e

what is the approach to use here to get the correct answer?

[VJesus12]

I think option A is irrelevant to the argument. So, it is out.

But, I don´t know how to discard the rest of the options.

Experts, may you help us please?