B) One of his secret tapes revealed that he had ordered a cover-up.
Explanation:
The tapes had more than 3500 hours of recorded material, and around 200 is referring to the Watergate scandal.<u> This scandal was an event in 1972. when burglars were caught stealing documents and wiretapping phones in the Democratic National Committee office in the Watergate complex. </u>This was connected to Nixon and his reelection campaign and he tried hard to cover up the scandal.
<u>However, when the tapes have been searched, they found initial plans of the cover-up where Nixon is forming a plan to make claims that national security was involved and his plans to prevent the investigation. </u>
Due to this disgrace, Nixon resigned on 8th of August 1974
