. . . . . . . . rich are not always kind. A. a B. an C. the D. no article

The correct answer is D. no article.

The word “rich” is an adjective, not a noun. It describes the noun “people.” Therefore, it does not need an article.

The other options are incorrect because they are articles. Articles are used to introduce nouns. In this case, the noun is “people.” The article “a” is used to introduce singular countable nouns that are not specific. The article “an” is used to introduce singular countable nouns that begin with a vowel sound. The article “the” is used to introduce specific nouns. In this case, the noun “people” is not specific, so it does not need an article.