This question tests the basic understanding of adverbs. The correct answer is B. To modify a verb, as adverbs primarily modify verbs, adjectives, or other adverbs, providing more information about how, when, where, or to what extent something is done. A. To describe a noun is incorrect because that is the function of an adjective. C. To replace a noun is incorrect because pronouns replace nouns, not adverbs. D. To connect clauses is incorrect because conjunctions connect clauses, not adverbs.