The Key Evidence in the Watergate Affair, Several Pieces of Which

The key evidence in the Watergate Affair, several pieces of which were deliberately erased or disposed of, were Nixon's

A) letters offering to pay the burglars to keep quiet.
B) nightly memos that detailed all the directives he gave to "the plumbers."
C) secret tape recordings of White House conversations and telephone calls.
D) extensive diaries which detailed the many illegal acts he authorized.