What is the main subject of the debate?

Man: We are having a debate on advertising tomorrow and I have to take part.
Woman: That’s interesting. I should like to hear what young people think about advertising.
Man:  Well, (1 [B]) we wouldn’t know what there is to buy if we didn’t have advertisement.
Woman: Yes, that’s true — up to a point. Advertisements provide information we need. If someone has produced a new article, naturally the seller wants to tell us about it.
Man: Yeah, and advertisements tell us which product is the best.
Woman: Do they? I don’t think so. Every manufacturer says that their product is the best, or at least tries to give us that impression. Only one can be the best, so the others are misleading us, aren’t they?
Man: Well, in a way, I suppose, but we don’t have to believe them, do we?
Woman: Are you saying that advertisements aren’t effective? (3[B]) (3[A]) I don’t think that intelligent business people would spend millions of dollars on advertising if nobody believed advertisements, do you?
Man: Perhaps not, but after all, it is their money that they are spending.
Woman: Is it? Maybe not. (2[C]) The cost of advertising is added to the price of the goods. You and I and ail the other people who buy these goods pay for the advertising!
Man: Ok, I suppose we get something for our money some information.
Woman: Yes, (3[C]) but don’t forget it is often misleading information, and sometimes harmful.