He claims they were too young to know what they were doing and were filled with illusions and daydreams because they read “bad” books.
In the fourth sentence of this paragraph, "they" is a (B.) subject pronoun.
A pronoun is a word that is used to replace a noun that, generally, has already been mentioned. Moreover, there are different types of pronouns since each of them serve a different purpose. Some of them are subject pronouns, object pronouns, possessive pronouns and reflexive pronouns. <u>The pronoun "they" in the fourth sentence of this paragraph is a subject pronoun because it is acting as the subject of the verb "sailed" and it is referring to a specific group of people</u> (the Tuatha Dé Dannan).
Simile. It's comparing using the word like.