It is part of the main conclusion—it doesn’t support any other conclusion. Also, there is never any claim that the media give more coverage to crime than the crime rate justifies.

This gets the argument’s support structure backward. The fact that the media base coverage decisions on the public’s interests provides evidence to believe the proposition in the question stem: the true cause of the media’s growing crime coverage is increased public interest.

It is an explanation for the phenomenon described (crime coverage has increased)—not a counterexample. The author agrees that the media devote more coverage to crime now, and then explains why this is so.

This claim is never made in the stimulus. Also, the proposition in the question stem isn’t a generalization, it’s a causal explanation.

This describes the role of the proposition in the question stem. It’s the author’s explanation, which he offers as an alternative to the theory that the media’s growing crime coverage is due to an increase in crime itself.