How will the right answer fit in terms of support and conclusion?

Only the right answer will be support that must be true if the conclusion is true, though in simpler terms it will also support the conclusion without bringing in anything new.

Highlight the main conclusion in the passage, if there is one:

Selling syndicated reruns of a popular network television program while the program is still running on that network can lead to decreased revenues for that network.

[CONCLUSION]. [BACKGROUND]. However, [SUPPORT].

This author changes the subject, making a conclusion about “decreased revenues” when there’s no mention or explanation given for that in the rest of the passage. What the passage explains instead is “an immediate ratings drop”. The right answer will make a connection between these two different subjects.

Map the wording of the answers to the wording of the passage:

(A) …tend to be long-running hits that are likely to decline soon.

The passage already said the producers are “assured of a successful show”. If that’s true, then this info doesn’t really matter. In any case, the conclusion about “decreased revenues” could still be true even if this isn’t, so the argument doesn’t “depend” on it.

(B) A drop in ratings has a negative effect on the network’s revenues.

This directly connects the wording of the support to the wording of the conclusion, without bringing in anything new. You love that. And if this isn’t true, then the whole explanation in the passage makes no sense.

(C) …includes some compensation for the network’s probable losses.

If there’s “compensation”, that wouldn’t really contribute to the “decreased revenues” the author claims in the conclusion. This is bringing in something new that is definitely not necessary for the conclusion to be true.

(D) …will usually prefer first-run episodes to reruns.

This brings in what audiences “prefer”, which isn’t mentioned in the passage. To connect that to “decreased revenues”, you’d need to add in your reasoning. That’s a dead giveaway that the argument doesn’t “depend” on this.

(E) Most programs are never sold into syndication.

The passage doesn’t say anything about “most programs”. And since the conclusion could totally be true even if this isn’t true, it can’t be the assumption you’re looking for.

(B) is the correct answer.