The passage tells us that agencies have successfully used a strategy for corporate clients in which they draw attention through controversial ads.
If this was successful, it is not the case that the controversial ads hurt more than they helped- that is, the value of the free publicity must have been greater than the loss of value from running controversial ads.
This is a soft must be false question.
A tells us that the only goal of an ad campaign is to persuade. If this were true- a campaign whose goal was only to draw attention (and by running controversial ads, would likely actually dissuade customers) would not be successful.
While this is not airtight (maybe controversy is persuasive), the passage does undermine the possibility that A is true.
