Correct Answer: A
Explanation:
The sentence's introductory clause seems to intend to describe the subject "he," but it begins with a verb that doesn't clearly connect to the rest of the sentence and is grammatically incorrect. Introductory clauses can begin with participles, which would make much more sense in this sentence by allowing the start of the sentence to connect clearly to the subject. Of the potential answer choices, only "Having been immersed" omits the incorrect verb and replaces it with a grammatically correct participle. The other answer choices don't make sense: "Immersion having happened" and "Immersion happening" don't clearly connect the first phrase to the subject, and "He who had been immersed" introduces a grammatical error by making the sentence contain two disconnected subjects, "He who had been immersed in the literature since childhood" and "he." The corrected sentence reads, "Having been immersed in the literature since childhood, he maintained an appreciation for it as an adult."