Answer: The sixth option that Haig gave to Nixon was that if Nixon resigned, the next President, Gerald Ford would pardon him.
Explanation: In his 1979 autobiography, A Time To Heal , Gerald Ford describes Haig's sixth option stating: " Haig said that according to some on Nixon's White House staff, Nixon could agree to leave [office] in return for an agreement that the new president -- Gerald Ford -- would pardon him."