The correct answer is A. That
Explanation:
In the English language, the words that/these/this/those are classified as demonstrative adjectives. This classification is because these words modify nouns acting as adjectives and they are often used to emphasize the noun or show their location. In the case of the demonstrative adjective "that" this modifies singular nouns that are far from the speaker, for example, "That cat is white" or "That movie was entertaining". Also, this differs from "this" that is used for singular nouns that are closer to the speaker and from "these" and "those" that are used for plural nouns. Thus, the word that is an example of a demonstrative adjective is "that".
