What part of speech describes an action or a state of being?

The correct answer is a verb. Verbs serve as the backbone of a sentence by indicating actions, occurrences, or states of being. For instance, in statements like "She runs" or "He is happy," "runs" reflects an action, while "is" signifies a state of being.

In contrast, adverbs modify verbs, adjectives, or other adverbs and help to provide context such as how, when, where, or to what extent something occurs. Nouns represent people, places, things, or concepts, and do not describe actions. Adjectives serve to modify nouns by providing more detail about their qualities or states, but they do not convey actions or being. Thus, verbs are the only part of speech among the options that fundamentally encapsulate actions or states of being.