Question

when president nixon finally turned over all the watergate tapes to the special prosecutor, the tapes
revealed that nixon had no knowledge of the break - in.
contained an important, unexplained gap of eighteen - and - a - half minutes.
showed that nixons right to \executive privilege\ had been violated.
did not incriminate nixon because the tapes were impossible to understand.

Explanation:

The Watergate tapes handed over by Nixon included an 18.5-minute gap, later linked to Nixon's secretary erasing potentially damaging content. The other options are incorrect: the tapes did show Nixon's awareness of the break-in cover-up, executive privilege was not violated by the tape handover itself, and the tapes were understandable and did incriminate Nixon.

Answer:

B. contained an important, unexplained gap of eighteen-and-a-half minutes.