Explanation

Creating a filter: the original sentence appears to be well formed. So we can move on to (B) and see what we're able to eliminate.

Finding objective defects: choice (B) is not grammatically a sentence. The phrases starting with "the shell-shaped region" and "which are much more likely" are both modifying phrases, so the grammatical subject "planets" has no verb, and there is no independent clause. So (B) is out. In choice (C), either the verb for "atmospheres" is supposed to be "is," or "atmospheres" has no verb, but either way it fails to be a grammatical sentence. Choice (C) is out. In choice (D), the meaning is distorted. All stars are more likely to contain life when they retain water, but that's not really what the wording of choice (D) is saying, and it muddles the relationship between the habitable zone and the likelihood of having water. So (D) is out. Choice (E) fails early on because it grammatically compares "planets" with "atmospheres of planets." The correct answer is (A).