Why did america fought against communism with the south in the Vietnam war?

When reading shakespeare, what is not an important reason for utililizing strategies such as paraphrasing and summarizing?

Which of the following episodes led to widespread charges that president reagan was not in adequate control? a. the u.s. retreat from lebanon after the bombing deaths of 241 u.s. marines as they lay sleeping in their barracks near beirut b. the trading of arms for hostages and the illegal funding of a right-wing insurgency in the iran-contra affair c. the sale of millions of acres of public lands to private corporations by the department of interior d. the proposal to congress, year after year, of federal budgets with huge deficits that ultimately ended up tripling the national debt

Government powers not provided to the national government in the us constitution but are rather given to the states by the 10th amendment is called?