Which of the following is an example of a morphophonological change?

• A. Knife -> knives (knives) involving voicing and spelling changes.
• B. Walk -> walked
• C. Cat -> cats
• D. House -> houses

Answer: (A)

Morphophonology is about how adding a morpheme can trigger sound changes in the surrounding form. In knife turning into knives, the plural suffix -es causes the final sound f (a voiceless consonant) to become v (a voiced consonant), and the spelling shifts from fe to ves. This demonstrates a real interaction between morphology (plural) and phonology/spelling, not just tacking on letters. The other examples involve simply adding a plural or past-tense ending without a root consonant changing its pronunciation or spelling in response to the morpheme, so they don’t illustrate this kind of phonological adjustment driven by morphology.