The United States intervened in Vietnam to.________ A.create a dependent colony out of South Vietnam that applied for U.S. statehood after a certain amount of time. . B. preserve an independent and democratic South Vietnam, but it withdrew and the country united under communism. . C. help the independent South Vietnam take control of its northern neighbor, and the country united under a representative democracy. . D. force the dependent South Vietnam to accept U.S. rule until it could establish independence from colonial rule and become an independent country