Explanation:

This question pertains to the constitutional provisions regarding the oath of office for the President of India. (A) Chief Justice: Article 60 of the Indian Constitution explicitly states that 'Every President and every person acting as President or discharging the functions of the President shall, before entering upon his office, make and subscribe in the presence of the Chief Justice of India or, in his absence, the senior-most Judge of the Supreme Court available, an oath or affirmation'. Therefore, the Chief Justice of India is the authority designated to administer the oath. This option is correct. (B) Speaker: The Speaker presides over the Lok Sabha and maintains decorum. Their role does not involve administering the oath to the President. Therefore, this option is incorrect. (C) Vice President: The Vice President is the ex-officio Chairman of the Rajya Sabha and acts as President in specific circumstances (e.g., death, resignation, removal of the President). However, they do not administer the oath to the President. Therefore, this option is incorrect. (D) Prime Minister: The Prime Minister is the head of the government and leads the Council of Ministers. Their role does not include administering the oath to the President. Therefore, this option is incorrect.