Between 1965 and 1968, the Vietnam War was fought primarily

From 1965 to 1968, much of the fighting took place on the ground in Vietnam’s forests and jungles. U.S. and South Vietnamese forces faced Viet Cong and North Vietnamese troops using guerrilla tactics in this terrain. The war also involved air and naval operations, but it was fought primarily in the jungle, so choice C is correct.

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