Short Answer 
The Truman Doctrine, established during President Truman’s administration, aimed to counter the spread of Communism by supporting countries threatened by it through financial, military, and political aid. This policy marked a significant shift in U.S. foreign policy, highlighting America’s commitment to prevent the spread of communism and support democratic nations.
Step 1: Understanding the Truman Doctrine
The Truman Doctrine was a significant U.S. foreign policy created during President Harry Truman’s administration. It aimed to combat the spread of Communism globally. The doctrine stated that America would support countries threatened by communist takeover through various forms of aid.
Step 2: The Purpose of Aid
The main purpose of the aid provided under the Truman Doctrine was to assist nations in their fight against communism. This assistance could come in various forms, which included:
- Financial Support: Helping countries manage their economies and maintain stability.
- Military Assistance: Providing weapons, training, and resources to bolster military efforts.
- Political Support: Strengthening non-communist governments and promoting democratic ideals.
Step 3: Significance and Conclusion
The Truman Doctrine marked a crucial shift in American foreign policy as it set the tone for U.S. involvement in global affairs concerning Communism. By openly supporting nations resisting communism, it aimed to prevent the ideological spread that could threaten democratic nations. In conclusion, option A regarding the Truman Doctrine is correct, emphasizing the U.S. commitment to counteract communism worldwide.