Which word contains a derivational suffix that changes the part of speech of its base word?
Show answer & explanation
Answer: C
walked: -ed is an inflectional suffix marking past tense; 'walk' stays a verb.
taller: The comparative -er is inflectional; 'tall' remains an adjective.
teacher: Correct. The agentive -er is derivational: it turns the verb 'teach' into the noun 'teacher.'
cats: Plural -s is inflectional; 'cat' remains a noun.
Inflectional suffixes (-s, -ed, -ing, comparative -er, -est) mark grammar without changing word class; derivational suffixes (-er agent, -ness, -ly, -tion) create new words, often in a new class.