- Noun
- Verb
- Adverb
- Adjective
The correct answer is “adverb.” In the sentence “He runs fast,” the word “fast” describes how the action of running is performed. It modifies the verb “runs.” Words that modify verbs, adjectives, or other adverbs by answering questions like “how,” “when,” “where,” or “to what extent” are classified as adverbs. Although “fast” can also be an adjective (e.g., “a fast car”), its function here is adverbial. It is answering the question “How does he run?” – He runs fast. An adjective, in contrast, would modify a noun or pronoun. Since “runs” is a verb, the modifier must be an adverb. Some adverbs, like “fast,” have the same form as their adjective counterparts, which can be confusing, but their grammatical role is determined by what they modify.
