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

Only the right answer will match the conclusion you highlight in the passage.

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

It is a mistake, however, to assume that answering this question is essential to improving the economy.

Newspaper columnist: [BACKGROUND]. [CONCLUSION]. [SUPPORT].

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

(A) Solving a problem never requires…

The author never said that, so no way it’s their conclusion.

(B) …would not necessarily enable people to find…

The author never said that either.

(C) The question of what caused the current recession…

This matches the background info in the first sentence. The author didn’t give any support for that.

(D) One need not ascertain the cause…

They’re trying to throw us off with weird wording, but this matches the conclusion. The author said that assuming you need to know the cause is a mistake, which is almost the same as saying you don’t need to know the cause.

(E) Long before the cause of myopia was known…

This matches the example used as support in the last sentence.

(D) is the correct answer.