This is the best answer. It captures the author’s rejection of the Marcusian view, and doesn’t say anything unsupported. If you don’t like (A) because of the phrase “while in principle there might be grounds for holding that advertising is detrimental to society,” please understand that this phrase doesn’t commit the author to agreeing that advertising is detrimental. This simply says that it might be possible for advertising to be detrimental – this is something we have no reason to think the author disagrees with. The passage focuses on rejecting the Marcusian view that advertising creates false needs, but the author isn’t defending advertising from other kinds of critiques. The only other answers that involve a rejection of Marcusian view include parts that are unsupported, so there’s no better answer than (A), which doesn’t say anything unsupported.

The author never suggests that Marcusian claims are “rationally justified.” So it wouldn’t make sense to finish the passage with this sentence.

The last paragraph is focused on showing the Marcusian critique is wrong. (C) doesn’t say anything about the Marcusian critique being wrong. So it wouldn’t make sense to finish the passage with this sentence.

The last paragraph is focused on showing the Marcusian critique is wrong. Although the author does point out certain effects of advertising that seem to be beneficial, the purpose of pointing out those benefits is not to argue that advertising is on balance more beneficial than harmful. The purpose is to show that, contrary to the Marcusian view, people are not necessarily deluded into a false kind of satisfaction by advertising. So it wouldn’t make sense to finish the passage with a general claim about the societal benefits of advertising; the point at the end should focus on the Marcusian view about false needs being wrong.

Very tempting, but wrong for several reasons. First, the Marcusians didn’t say that there were only “few people who are unable or unwilling to distinguish real from false needs.” The Marcusians believed that people generally can’t distinguish between these kinds of needs. So the phrase “those few people” doesn’t capture any claim that the Marcusians actually made. Second, the Marcusians didn’t assert that advertisers exert “economic” power over people. They asserted that advertising has manipulative, psychological power over people.