How about choice 5. In 1960 Nixon, who won the reported popular vote, knew that he had actually won the electoral vote, because of obvious fraud (e.g.--losing areas with 500 inhabitants by 15,000 votes). He decided not to do what Gore was to do in 2000 because he realized that it could destabilize the government, at a time we were about to take out the Red incursion into the Western hemisphere, by invading Cuba and overthrowing Castro.
His patriotism led him to concede, but the entire affair led to his embitterment, which was the root of the whole Watergate matter.