Identify the article in the sentence: "I saw a cat."

In the sentence "I saw a cat," the word "a" serves as the article. Articles are a specific type of adjective that introduces a noun and helps to indicate a non-specific or specific instance of that noun. In this case, "a" specifies that the speaker saw one cat, but it doesn't refer to any particular cat; it's indefinite.

The use of "a" is indicative of an indefinite article, which is used before a singular noun that is countable and begins with a consonant sound. Therefore, identifying it as the article in this sentence is correct, as it fulfills the function of pointing out the noun "cat" without specifying which cat is being referred to.