Who can play . . . . . . . . piano in your class?

The correct answer is Option D: none of the above. In this sentence, the indefinite article "a" or "an" is not required before the word "piano." The sentence is asking about a specific skill possessed by someone in the class, which is playing the piano. Since the sentence doesn't require any article, the correct option is D, which indicates that none of the provided options is suitable in this context.