The custodian of the Indian Constitution is the Chief Justice of India. The Constitution is the supreme law of the land and the Chief Justice of India, as the head of the judiciary, plays a crucial role in safeguarding and interpreting its provisions. Option 1, the President of India, is incorrect because while the President has a crucial role in the functioning of the government, they are not the custodian of the Constitution. Option 3, the Prime Minister of India, is also incorrect as the Prime Minister is the head of the government and not specifically entrusted with the custody of the Constitution. Similarly, option 4, the Chairman of Rajya Sabha, is incorrect as the Chairman of Rajya Sabha presides over the upper house of the Parliament and does not have the custodial responsibility of the Constitution.