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

Only the right answer will complete the conclusion supported by the passage.

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

The right answer will fill in the conclusion that starts right before the blank, but nothing needs highlighting.

Sociologist: [BACKGROUND]. But since [SUPPORT], this strategy ______.

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

(A) can save those cultures…

This isn’t supported by the passage at all. If every tradition is “essential”, then “abandoning” them would definitely be a negative thing. So “save” has no business being in there. The “capable of…” part also brings in totally new wording that doesn’t map to anything stated in the passage.

(B) will ensure the elimination of a culture…

Honestly, I kinda hate the wording of this. The conclusion only says it’s essential to a culture’s “identity”, so I’m not sure the culture itself would also be eliminated. Buuut, at least this maps to the rest of the support, so it survives until something better shows up.

(C) …only those cultures studied by anthropologists

The passage doesn’t make any distinction between cultures that are “studied by anthropologists” and cultures that aren’t. So there’s no support for what only the ones that are studied can do.

(D) constitutes the most effective response to the threat of cultural decay

It should be clear the author is trying to disagree with “some anthropologists”. This matches their claim, so it’s definitely not meant to be the author’s conclusion.

(E) …have been adopted only recently

There’s nothing in the passage about how old or “recent” these traditions are, so we have no support for a conclusion about just those kinds of traditions.

(B) is the correct answer.