What caused the release of taped White House conversations during the Watergate scandal?

The Supreme Court ruled that the tapes had to be handed over.
Criminals discovered the tapes during a break-in at the Watergate.
President Nixon willingly released the tapes to the Senate.
A White House staff member released the tapes against Nixon’s wishes.

In April 1974, the House Judiciary Committee subpoenaed the tapes of 42 White House conversations that dealt with the 1972 break-in at the Democratic National Committee’s headquarters at the Watergate Office Building and the subsequent attempted cover up.

At the end of that month, President Richard Nixon released edited transcripts of the White House tapes, citing executive privilege and national security as the reason he needed to withhold certain material. The Democratic-led Judiciary Committee, however, rejected the redacted transcripts, saying that they failed to comply with the subpoena.

Explanation:

d.summerains, the last one

powers  are  denied  to the  national governmentin three distinct ways: some  powers, such as the  power  to levy duties on exports or prohibit the freedom of religion, speech, press, or assembly, are expressly  denied  to the  national government  in the  constitution.