Which U.S. foreign policy aimed to prevent the spread of communism in the Western Hemisphere?

The correct response is the Monroe Doctrine. This policy, articulated in 1823 by President James Monroe, established a principle that aimed to deter European intervention in the affairs of the Americas. It declared that any attempt by European nations to colonize or interfere in the Americas would be viewed as an act of aggression, warranting U.S. intervention.

Although the timeframe of the Monroe Doctrine was much earlier than the Cold War and the specific fear of communism, its underlying principle of safeguarding the Western Hemisphere from external influence aligns with the broader objective of U.S. foreign policy to prevent European powers, and by extension, communism, from gaining a foothold in the region.

The other options represent different U.S. foreign policies with their unique focuses and contexts: the Marshall Plan was aimed at rebuilding Europe post-World War II, the Truman Doctrine specifically addressed the containment of communism globally through political and military support, and the Eisenhower Doctrine was aimed at the Middle East, emphasizing assistance to countries resisting communism. Each of these policies, while significant, does not fit the question about preventing the spread of communism specifically in the Western Hemisphere like the Monroe Doctrine does.