Which of the following is NOT an example of an inflectional suffix?

The choice indicating that "-ful" is not an example of an inflectional suffix is accurate because inflectional suffixes are used to modify a word's tense, number, or case without changing its class or meaning significantly. Examples like "-ed," "-er," and "-ing" serve specific grammatical functions:

• The suffix "-ed" indicates past tense for verbs (e.g., "walk" becomes "walked"),

• "-er" can denote a comparative form for adjectives (e.g., "tall" becomes "taller") or signify a person who performs an action (e.g., "teach" becomes "teacher"),

• "-ing" signifies an ongoing action or activity (e.g., "run" becomes "running").

In contrast, "-ful" is a derivational suffix that changes the meaning of the base word and alters its grammatical category. For example, when "-ful" is added to "beauty," it transforms the word into the adjective "beautiful." This represents a shift in the word's function, marking it distinctly as a derivational suffix rather than an inflectional one. Hence, this distinction is crucial in understanding the roles of different suffixes in English word formation.