___ was/were most effective in convincing the American public that the war was not winnable. A. Body counts
B. The Tet Offensive
C. The actions of Students for a Democratic Society
D. The invasion of Cambodia

B. the Tet Offensive.

Explanation:

Though U.S. and South Vietnamese forces managed to hold off the attacks, news coverage of the massive offensive shocked the American public and eroded support for the war effort. Despite heavy casualties, North Vietnam achieved a strategic victory with the Tet Offensive, as the attacks marked a turning point in the Vietnam War and the beginning of the slow, painful American withdrawal from the region. The offensive was an attempt to foment rebellion among the South Vietnamese population and encourage the United States to scale back its involvement in the Vietnam War and the attacks efforts proved to be worth.

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