Which of the following best explains why the 25th amendment was first used? a. it was used to fill the vacant office of the president after the death of president william henry harrison. b. it was used to fill the vacancy left after the resignation of vice president agnew during the nixon administration. c. after the resignation of president nixon, the 25th amendment was used to place vice president gerald ford in the office of the president. d. after president kennedy was assassinated, the 25th amendment was used to place vice president lyndon johnson in the office of the president.