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

Only the right answer will accurately describe what kind of support, conclusion, or background the claim is.

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

increasing urbanization may actually reduce the total amount of pollution generated nationwide.

Although [BACKGROUND], [MAIN CONCLUSION]. [SUPPORT]. Thus, [INTERMEDIATE CONCLUSION].

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

(A) …the conclusion that people should live in large cities.

Even if you’re not sure what the right answer will say, you know the author never said “people should live in large cities”, so that can’t be their conclusion.

(B) …call into question the claim that large cities are generally more polluted…

Haha, nice try. But we all saw the author explicitly say that in the first sentence, so no way they would “question” it.

(C) …merely to introduce the topic…plays no logical role.

That would describe background info, not the main conclusion. Everything after the “claim” is there to back it up.

(D) It is a premise…

Nope, it’s not used to support anything else. And you know “Although” means the two parts of that sentence disagree. So no way one is supporting the other.

(E) It is a claim that the rest of the argument is designed to establish.

That’s pretty much the textbook definition of “main conclusion”. Love it.

(E) is the correct answer.