Between A and D, I prefer D. Not sure how to rule out A.

This sentence contains an awkward prepositional phrase; on account of living does not clearly express the relationship between the second part of the sentence and the first, which is a cause-effect relationship. While on account of does indicate a cause-effect relationship, it cannot be used to introduce an entire subordinate clause. Introducing a subordinate clause can be done concisely with a single word like because or since.

Choice D is correct. It replaces on account of living with because it lives, which is concise and grammatical; it lives displays pronoun-antecedent agreement (it refers to the mountain goat) and provides the subordinate clause with both a subject and a verb.

Choice B uses the construction being, a construction that should be avoided in most cases. They is a plural pronoun incorrectly referring to the singular antecedent, the mountain goat.

Choice C correctly replaces the wordy on account of with because of; however, this subordinate clause does not contain a main subject or verb and is therefore ungrammatical.

Choice E retains the original mistake and introduces a pronoun-antecedent agreement error.

Choice D is correct.

vk_vinayak wrote:Between A and D, I prefer D. Not sure how to rule out A.