Explanation:

Third option is correct. All doubts and disputes in connection with election of the President are inquired into and decided by the Supreme Court whose decision is final.
The election of a person as President cannot be challenged on the ground that the Electoral College was incomplete (i.e., existence of any vacancy among the members of Electoral College).
If the election of a person as President is declared void by the Supreme Court, acts done by him before the date of such declaration of the Supreme Court are not invalidated and continue to remain in force.