Answer :
The Credibility gap during the Vietnam war + the President Nixon's involvement in Watergate led to loss of trust in the federal government.
Credibility Gap
During the Vietnam war, the leak of Pentagon Papers, highlighted the war crimes and the lies of Federal Government to the world. Due to which Political Pundits used the phrase “credibility gap”.
As per the question, the loss of trust in the federal government was caused by two things, first the Credibility gap during the Vietnam war, and secondly the President Nixon's involvement in Watergate. Hence, the option A is correct.
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