The answer is: E
Explanation
The correct option is E: Yes, he has to answer questions up to the point where he may incriminate himself.
This is because, according to the principle, any person who is supposed to be acquainted with the facts and circumstances of the case is bound to answer truly all questions put by the police officer, except those that would expose him to a criminal charge or penalty. In this case, A is a witness to the incident where one man assaulted another, and he is also involved in the assault, but the police officer does not know that. Therefore, A has to answer the questions related to his role as a witness, but he can refuse to answer any questions that would reveal his role as an assailant. A can invoke the right against self-incrimination under Article 20 (3) of the Constitution of India, which states that no person accused of any offence shall be compelled to be a witness against himself.
However, A cannot claim this right from the beginning, as he has not been formally accused of any offence at the time of interrogation. He can only claim this right when his answers would have a tendency to incriminate him.