a joke that is a play on words is a\no riddle.\no comic.\no pun.\no prank.

Brief Explanations:

A pun is a form of word - play that exploits multiple meanings of a word or words that sound similar but have different meanings. A riddle is a question or statement intentionally phrased so as to require ingenuity in ascertaining its answer. A comic is related to comedy or a person who performs comedy. A prank is a mischievous act.

Answer:

C. pun