Hi,
I like your question - cutting to the point of how to approach this problem in a time crunch while focusing on some basics. Here's a dissection for your further edification:
B - The "noun as adjective" must always come first, the second noun is the subject matter.
You're correct, the adjective must precede the modified noun. B reverses that author and has a more specific noun "Melville" modify a more general noun "the author." That doesn't make sense as clearly the author is meant to modify Melville.
C- "The author named" is too wordy
I normally dislike using concision to justify an elimination but you're quite right. "Named" is excess language and the alternative in A is more concise with no loss in meaning.
D- Herman Melville and Walt are covered in COMMAS which make them non essential and thus changing the meaning
I likewise normally dislike using meaning to justify an elimination but in this case doing so is necessary. You are correct that the commas make Melville and Whitman modifiers and thus not essential to the sentence. Instead, the main actors are "the author" and "the poet." Clearly that doesn't make sense so out with D!
E- "Had been" changes the meanin
E is an example of an answer choice that shouldn't be eliminated just based on meaning. "had been" is the verb "to be" in the past perfect tense. The past perfect tense is used to distinguish an earlier past event from another past event. In this case, it is improper to use the past perfect for two reasons: 1. There is no other past event or action in the sentence to compare with "had been" 2. According to the sentence, Whitman and Melville are
greatly beloved by generations past and present. The "present" in the sentence suggests that the present tense of "to be" is preferred over the past perfect. Meaning is at play, but I'd rather see you use one of the two reasons as your justification instead.
Either way, great work and I think you have a great way of building your "take aways" for these types of problems. Keep up the good work.
-Chris