Which of the following is an analogy?

An analogy is saying something is like something else to make some sort of explanatory point. For example, “Life is like a box of chocolates—you never know what you're gonna get.”

op: object of preposition

the answer is:

when will (v) the books (n) be (v) due?

nouns refer to people (other than pronouns), places and things, whereas verbs describe actions and are usually part of the predicate of a sentence. finally, pronouns can work as nouns and identify the participants in speech.

in the example sentence, "will" is a verb part or auxiliary verb, "be" is an infinitive verb and "books" is a plural noun.