Why did Nixon resign from the presidency in the midst of the Watergate

Why did Nixon resign from the presidency in the midst of the Watergate investigation?

A) The House of Representatives had started impeachment proceedings based on evidence revealed in the tapes that Nixon could not withhold from investigators due to a Supreme Court ruling.
B) Both he and his vice president had been involved in a bribery scandal and had no choice but to resign.
C) Nixon admitted under oath that he had been one of the “plumbers” who broke into the Watergate.
D) Newspaper reporters revealed that Nixon had secretly allowed a communist spy to work in the federal government.

ANSWER
Answer: A