The correct option is D Could you tell me the way to Vidthwata University?
The question must ask for directions to go to the university.
Option A: This question is a rather formal one and the tone isn't very conversational.
Option B: This question does not fulfill the required goal. By asking 'which way', the person wouldn't be able to put his complete thought across, as it does not ask for directions. He may only get an answer as to which direction to go. This does not match the given description.
Hence options A and B are incorrect.
Option C: This question is most suitable as it generally asks for the way towards the university. It is non-specific and conversational.
Hence option C is correct.
Option D is incorrect because B is not a suitable answer.