Question

The Pentagon Papers _____.

were not a political problem for Nixon or any of his cabinet
were a secret study of the history of U.S. involvement in Vietnam
were leaked to the New York Times by Robert McNamara
were prohibited from being published in a decision by the Supreme Court

Answer 1

The answer would be, "were a secret study of the history of U.S. involvment in Vietnam"

Step-by-step explanation:

Answer 2

The Pentagon Papers "were a secret study of the history of U.S. involvement in Vietnam," since their conclusions were highly controversial and the Johnson Administration initially blocked their release.