You Are Watching a Game Show That Gives the Answer

Multiple Choice

You are watching a game show that gives the answer and contestants give the question.One of the items was,"An arbitrary pairing between a sound or symbol and a meaning." Not one of the contestants knew the answer,but you do! What is the question?

A) "What is grammar?"
B) "What is a heuristic?"
C) "What is a word?"
D) "What is language?"