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

Only the right answer will accurately describe the support and conclusion, and the only that accurately describes a flaw therein.

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

the twelve-month schedule is to be preferred insofar as academic learning is concerned

[SUPPORT]. [BACKGROUND]. We should conclude, …that [CONCLUSION], since [SUPPORT].

This argument makes a comparison, though a very incomplete one. It gives evidence against the “nine-month schools”, but absolutely no evidence for the “twelve-month schedule” it recommends.

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

(A) …the comparative worth of academic and nonacademic….

Nope. The conclusion is only about “academic learning”.

(B) …distinction between two groups.

The comparison in the passage is between school schedules, not “groups”.

(C) …a certain undesirable result is correlated with only one of them.

Love how this maps. The “undesirable result” is that students “forget their schooling”. And the support pretty much exactly says it’s “correlated with only one of them”, without ever addressing if a one-month break is short enough to fix the problem.

(D) …was adequately representative of children in the population…

You can’t pick this unless it maps to specific wording in the passage about a small or unrepresentative sample. You’re a lawyer now. You never just assume these things. There’s nothing about the sample vs. the population in the passage.

(E) claims to accept a view, but then rejects it…

What “view” would this map to? The author didn’t “reject” anything, they only said one thing was “preferred” over another.

(C) is the correct answer.

Common pattern/s in this question: The right answer becomes fairly recognizable if you know you’re looking for something that calls out the incomplete comparison in the argument.