The correct answer is D.
McCarthyism is the practice of making accusations or treason or disloyalty without proper or no evidence.
This term has its origin in the period in the United States known as the Second Red Scare, lasting from 1940's to 1950's. During that period there was heightened political repression and a fear spreading campaign, accusing many of collaborating with Soviet Union spies and spreading Communism in the U.S.
During the McCarthy area, hundreds of Americans were accused of being Communists, they became subjects of aggressive investigations and questioning, many were accused falsely or without any proper evidence.
