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

Only the right answer will add support for the conclusion.

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

the residents of Sierra should vote in favor of a local tax to fund construction of the proposed road.

Developer: [BACKGROUND]. [SUPPORT], and [SUPPORT]. Therefore, [CONCLUSION].

The conclusion changes the subject by bringing in “a local tax to fund construction”, which wasn’t mentioned anywhere else in the passage. The right answer will have to connect that to the wording of the support.

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

(A) If a construction project is necessary…

Stop. Where did the author say the project is “necessary”? That’s right, they never did. This doesn’t map to the situation described in the passage, so it doesn’t “justify” the argument.

(B) The residents of a town should not vote in favor of a local tax…

This is a rule for when not to vote for a tax, which can’t support a conclusion that people “should vote in favor” of the tax.

(C) …by means of a tax rather than debt.

The author never compares taxes and debt. They never even mentioned “debt” at all, so this doesn’t really map to the argument or “justify” the conclusion.

(D) …should be required to pay a tax…

This is mischaracterizing the author’s argument. It’s not about who “should be required” to pay, it’s about whether to vote in favor of the tax or not.

(E) Anyone who would benefit…should vote in favor of a local tax…

Boom! The first part maps perfectly to the author saying the project “would benefit every Sierra resident”. And it makes exactly the same recommendation, without bringing in any new and irrelevant stuff.

(E) is the correct answer.