The correct answer is option 1: 6 months. According to the Indian Constitution, the President`s seat can be left vacant for a maximum duration of 6 months. This provision is mentioned in Article 56(1), which states that if the President`s office becomes vacant due to death, resignation, or removal, the Vice President will act as the President until a new President is elected. If a new President is not elected within 6 months, then the Vice President will continue to act as the President until a new President is elected. It is important to note that during this period, the Vice President exercises the powers and performs the functions of the President, but does not hold the title of the President.