D. American leaders worried that a Communist victory in Korea would
lead to the spread of Communism throughout Asia.
Explanation:
The Americans had primarily dealt with communism through the idea of the Domino Effect in which if one nation falls to communism, the nations nearby would follow suit and therefore creating a "domino" like effect.
The Boston Massacre had a major impact on relations between Britain and the American colonists. It further incensed colonists already weary of British rule and unfair taxation and roused them to fight for independence.
