Correct Answer:
A. Don't talk so loud
An adverb modifies a verb, an adjective, or another adverb, providing information about how, when, where, or to what extent an action occurs. In option A, "loud" functions as an adverb modifying the verb "talk," describing how one should not talk. While "loud" can be an adjective, here it directly describes the manner of talking. Options B, C, and D primarily feature adjectives: "next" modifies "house," "quick" modifies "he" (via "is"), and "dark" modifies "night." These words describe nouns or pronouns, making them adjectives, not adverbs. The key is identifying the word that describes the action.