Inflectional morphemes are described as:

• A. Endings of words (ing, s, es, est) functioning as suffixes.
• B. Prefixes that create new words.
• C. Isolating morphemes with no change in word form.
• D. Infixes that convey aspect.

Answer: (A)

Inflectional morphemes add grammatical information to a word without changing its part of speech, and they typically show up as endings. In English they almost always appear as suffixes that signal number, tense, or degree. Examples include -s or -es for plural nouns or third-person singular verbs (cats, runs), -ed for past tense (walked), -ing for present participles (walking), and -er/-est for comparisons in adjectives (taller, tallest). This makes endings functioning as suffixes the clear way to describe inflectional morphemes, because they modify meaning without creating a new word or changing its word class.

Prefixes, by contrast, are derivational and create new words or shift meaning. Describing morphemes as isolating with no form would refer to zero morphemes, which isn’t about adding grammatical information. Infixes that convey aspect aren’t a standard feature of English inflectional morphology.