Which of the following refers to a word that modifies a noun, pronoun, or phrase?

The key to understanding this question lies in the functions of different parts of speech. An adjective is a word that specifically modifies a noun or pronoun, providing additional information about its quality, quantity, or identity. For instance, in the phrase "the red car," the word "red" is an adjective that describes the noun "car," giving us more detail about it.

By contrast, an adverb modifies a verb, adjective, or other adverbs, typically indicating manner, degree, frequency, etc. A noun identifies a person, place, thing, or idea, while a verb expresses an action or state of being. Recognizing the distinct roles of these parts of speech clarifies why the correct choice in this instance is the adjective, as its primary function is to enhance or clarify a noun or pronoun.