Which part of speech describes or modifies a noun?

The choice that correctly identifies the part of speech that describes or modifies a noun is an adjective. Adjectives provide additional information about a noun, including characteristics such as size, color, quantity, and quality. For example, in the phrase "the blue car," the adjective "blue" modifies the noun "car" by specifying its color.

Pronouns replace nouns and do not modify them, which distinguishes them from adjectives. Adverbs modify verbs, adjectives, or other adverbs, but they do not serve the purpose of describing nouns. Conjunctions connect words, phrases, or clauses but do not provide descriptive information about nouns. Therefore, the role of adjectives in modifying nouns makes them the correct answer to this question.