What is the function of articles in a sentence?

Articles serve the critical function of introducing nouns in a sentence, helping to clarify whether a noun is referring to a specific entity or a general one. In English, articles can be definite (the) or indefinite (a, an). For example, saying "the cat" specifies a particular cat, while "a cat" refers to any cat in a general sense. This distinction plays a significant role in sentence construction and meaning by guiding the reader's understanding of what is being discussed.

The other options do not accurately reflect the function of articles. Modifying verbs pertains to adjectives or adverbs, denoting possession is related to possessive pronouns or constructions, and expressing action involves verbs. Thus, the introduction of nouns is the primary function of articles, making this choice the most accurate.