Which of the following is an example of a definite article?

The choice of "the" as the correct answer is based on its role as a definite article in English grammar. A definite article is used to refer to a specific noun that is already known to the reader or listener. For example, when you say "the book," it indicates a particular book that is distinct and identifiable within a given context, contrasting it with indefinite articles or other determiners that do not specify the noun in the same way.

In English, "the" is the only definite article, while other choices like "and," "a," and "some" serve different grammatical functions. "And" serves as a conjunction to connect words or phrases, "a" is an indefinite article used to refer to a non-specific item, and "some" functions as a determiner that can indicate an unspecified quantity or number. Each of these has a unique role in sentence structure that does not equate to the specificity conveyed by "the." Understanding the function of definite articles helps clarify the distinctions between different types of articles and their applications in English language use.