An action in a sentence can be represented in two ways, namely active and passive voice.
The passive voice always uses the past participle form of the main verb irrespective of any tense. Only the auxiliary verbs depend upon the sentence given in the active voice.
The correct answer is C)Is the question being answered by him?
Option C is correct as the subject of the given sentence ( he) comes in the place of the object (the question) and vice versa.
Also, as the given sentence is an interrogative sentence, the helping verb comes before the subject, the transformed sentence is also in the present continuous tense and 'being' is used with the past participle form of the main verb (answer).
Options A, B, and D are wrong as the given sentence is interrogative, the helping verb 'is' comes before the subject of the transformed sentence, and verb +ing form cannot be used in the transformed sentence respectively.