Which of the following is an example of an inflectional morpheme?

An inflectional morpheme is a type of morpheme that modifies a word's tense, number, aspect, mood, or case without changing its core meaning or deriving a new word. The suffix "-ed" in "played" is an example of an inflectional morpheme because it indicates that the action took place in the past. This suffix alters the verb form from its base form "play" to its past tense form "played", showcasing how inflectional morphemes function to convey grammatical information.

In contrast, the other options provided are derivational morphemes, which change the meaning of the word or create a new word altogether. For instance, "un-" in "undo" negates the meaning of the verb "do". The suffix "-er" in "faster" indicates a comparative form, applying to the adjective "fast" but in a way that signals a change in form rather than tense. Similarly, "pre-" in "prehistoric" is a prefix that denotes something that occurs before a certain period, thus altering the original meaning of "historic" rather than changing its grammatical function.