Which of these groups was so strongly affected by american anti communism that hey were forced to disband apex?

 the answer to this question is the weavers,

The group  members were notably Pete Seeger and Lee Hays, Ronnie Gilbert, and Fred Hellerman and had formed the group in 1948.
The Weavers were an American folk music quartet based in the Greenwich Village area of New York City. They were forced to disband following congressional inquest into the group led by McCarthyism, which even convicted Seeger for contempt.