. . . . . are you doing now? A. When B. What C. Who D. Whose

The correct answer is “What”.

The question “What are you doing now?” is asking about the action that the person is currently doing. The other options are not relevant to the question.

• “When” is asking about the time.
• “Who” is asking about the person or people involved.
• “Whose” is asking about the ownership of something.

The word “what” is used to ask about the identity or nature of something. In this case, it is being used to ask about the action that the person is currently doing.