Final answer:
The word in italics, 'None' of the books are mine, is an example of an indefinite pronoun.
Step-by-step explanation:
The word in italics, None of the books are mine, is an example of an indefinite pronoun. Indefinite pronouns are used to refer to non-specific people, places, or things. In this case, 'none' is an indefinite pronoun because it refers to an unspecified number of books that do not belong to the speaker. 'None' is also an example of a pronoun because it is used in place of a noun, which in this case would be the books.