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

Only the right answer will accurately describe the support and conclusion.

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

the health of a newborn depends to a large extent on the amount of food available to the mother during her pregnancy.

[SUPPORT]. This indicates that [CONCLUSION].

The author changes the subject in a major way, bringing “the health of a newborn” and the “amount of food available” into the conclusion. That’s totally different wording, with different meanings, from “birth weights” and “crops” in the previous sentence. The right answer will probably call that out.

Aaaand you sniffed out that the author made a cause-and-effect claim in the conclusion, right? They’re effectively saying babies’ health is an effect of how much food is available. The support only says there’s a correlation between the two, so you should expect the right answer to call that out too.

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

(A) inferring from a claimed correlation between two phenomena that two other phenomena are causally connected to one another.

Boom! This pretty perfectly describes the passage. The “correlation” is between birth weights and the success of crops, but the conclusion says the availability of food “causally” effects newborn health.

(B) inferring from the claim that two phenomena have fluctuated together that…must be the sole cause…

This gets close, but be careful. Fluctuated means a number went up AND down. The passage only says “The more…, the higher…” It doesn’t actually say anything fluctuated. The word “sole” is maybe more obviously problematic, since the conclusion definitely does NOT say it’s the only cause.

(C) inferring from records concerning a past correlation…that that correlation still exists.

I like the first part since the first sentence of the passage mentions the past. But the conclusion isn’t about “that correlation”. Also there’s nothing in the conclusion that sounds like “still exists”. It may not seem critical but that wording has to map to similar wording in the passage, otherwise this can’t be the right answer.

(D) …existence of a common cause…and then presenting a hypothesis about that common cause.

A common cause would mean something has multiple effects, but that doesn’t align with the passage. It’s just one thing causing one other thing.

(E) inferring the existence of one causal connection from that of another…

Love the first part. Remember “Inferring” always wants to line up to the conclusion, which did make a causal connection. But there was only one causal connection, so “another” doesn’t map to anything stated in the passage.

(A) is the correct answer.