The correct answer is option 4: President. The President of India has the authority to appoint other ministers of the Union Cabinet, apart from the Prime Minister. The President appoints ministers on the advice of the Prime Minister, who is the head of the government. The Prime Minister recommends individuals who should be appointed as ministers to the President. Once the President receives the recommendation, he or she approves the appointment and the ministers assume their positions in the Union Cabinet. It is important to note that the Speaker, Chief Justice of the Supreme Court, and Vice President do not have the power to appoint ministers of the Union Cabinet.