Which morpheme type enhances word meaning but does not change grammatical function?

The correct choice is derivational morpheme because it modifies the meaning of a word and can create new words, but it does not alter the grammatical function of the base word to which it is added. For example, adding the prefix "un-" to the adjective "happy" creates the new word "unhappy," which retains its adjective grammatical function while changing its meaning.

While inflectional morphemes also impact word formation, they serve primarily to indicate grammatical changes, such as tense or number, rather than enhancing meaning in a way that generates a new word. Affix morphemes, which include both prefixes and suffixes, can be either derivational or inflectional, so they do not exclusively enhance word meaning without changing grammatical function. Bound morphemes cannot stand alone and must be attached to other morphemes, but they do not directly address the question about enhancing meaning without changing grammatical function. Thus, derivational morphemes are specifically designed to enrich meaning while maintaining the grammatical role of the words they modify.