In "They were quite late," how does the word "quite" function grammatically?

In the sentence "They were quite late," the word "quite" functions as an adverb. Adverbs are words that modify verbs, adjectives, or other adverbs, providing more information about how an action is performed or to what degree a quality is present. In this context, "quite" modifies the adjective "late," indicating the extent to which they were late. It enhances the meaning of "late," suggesting that they were very late or significantly late.

This clarification about the degree applied to the adjective is a key characteristic of adverbs, reinforcing their role in providing more detail within the sentence. The other options do not accurately fit the role that "quite" plays in the context provided.