• In grammar the basic rule to form a sentence is subject+verb+predicate.
• If the sentence is interrogative then the question word comes before the subject and if the sentence has question word and helping verb then question word and helping verb come before the subject.
• From the above given explanation, we can conclude that option C is the correct answer.
• As the sequence in option C is correct.
• In option A verb is before the question word, so it is not the correct option.
• In option B helping verb come before the question word, so it is not the correct answer.
• Option D is also not in the correct order, so option D is not the correct answer.

Hence, option C is the correct answer.