What Was the Significance of the "Nixon Tapes" in the Watergate

What was the significance of the "Nixon tapes" in the Watergate scandal?

A) They had been secretly recorded at the order of the prosecutors without Nixon knowing, proving to be an invasion of privacy.
B) They revealed Nixon's willingness to cooperate with investigators, as he supplied them early on in the case.
C) They confirmed Nixon's active role in the cover-up and suggested that certain segments had been erased.
D) They established a precedent for only providing transcriptions of recordings in court cases, as the two versions matched.
E) They confirmed that the White House had not tried to offer "hush money" to witnesses and protected all of Nixon's advisors from time in prison.