The correct answer is (a) President of India.
The President of India is the constitutional head of state of India. The President is the supreme commander of the Indian Armed Forces and the head of the Union Government. The President is elected by an electoral college consisting of elected members of both houses of Parliament and the legislative assemblies of all states.
The Vice-President of India is the second-highest constitutional office in India. The Vice-President is elected by an electoral college consisting of elected members of both houses of Parliament. The Vice-President is the ex-officio chairman of the Rajya Sabha and the President of the Rajya Sabha in the absence of the President.
The Prime Minister of India is the head of government of India. The Prime Minister is appointed by the President and is the leader of the party or coalition that has a majority in the Lok Sabha. The Prime Minister is responsible to the Lok Sabha and can be removed from office by a vote of no confidence.
The Speaker of the Lok Sabha is the presiding officer of the Lok Sabha. The Speaker is elected by the members of the Lok Sabha. The Speaker is responsible for maintaining order in the Lok Sabha and for conducting the business of the House.
The President of India has the authority to preside over a joint session of Parliament. A joint session of Parliament is a meeting of both houses of Parliament, the Lok Sabha and the Rajya Sabha. The President presides over a joint session of Parliament when there is a disagreement between the two houses on a bill.