The correct answer is option 'D' - Both.

The President of India, during his tenure, is immune from criminal proceedings as well as arrest and imprisonment. This immunity is granted to ensure the smooth functioning of the office of the President and to protect the dignity and authority of the position. Let's discuss each aspect in detail:

1. Immunity from Criminal Proceedings:
During the tenure of the President, he enjoys immunity from criminal proceedings. This means that the President cannot be prosecuted or held liable for any criminal offense committed during his presidency. This immunity extends to both civil and criminal cases. It is important to note that this immunity is not absolute and can be lifted if the President's actions are found to be in violation of the Constitution or if he is involved in any criminal activity unrelated to his official duties.

2. Immunity from Arrest and Imprisonment:
The President is also immune from arrest and imprisonment during his tenure. This means that he cannot be arrested or imprisoned for any reason whatsoever, except in the case of a serious criminal offense. This immunity is granted to protect the President's independence and to ensure that he is able to perform his duties without fear of coercion or interference. However, it is important to note that this immunity does not extend beyond the President's term in office.

The immunity granted to the President is in line with the principle of separation of powers and the need for an independent and impartial head of state. It ensures that the President can discharge his constitutional duties without being unduly influenced or harassed by external forces. However, it is important to strike a balance between immunity and accountability. The President is still accountable to the Constitution and can be impeached by Parliament for any violation of the constitutional provisions.

In conclusion, during his tenure, the Indian President is immune from criminal proceedings as well as arrest and imprisonment. This immunity is granted to protect the independence and authority of the office of the President. However, it is important to ensure that this immunity does not compromise the President's accountability and the rule of law.