Answer:
The correct answer is B. The Truman Doctrine prevented the spread of communism into third world countries.
Step-by-step explanation:
On March 12, 1947, President Harry S. Truman made a statement to the US Congress, which went down in history as the so-called Truman Doctrine. According to this doctrine, it should become the foreign policy principle of the United States of America "to assist free peoples who oppose the intended subjugation by armed minorities or external pressure". Truman said the US was ready to respond to the Greek government's urgent appeal for economic and military support in the Greek Civil War. Even Turkey, which was in a similar situation as Greece, should receive American aid.
The Truman doctrine marked the end of the US war coalition with the Soviet Union and marked the beginning of the Cold War. With it began the financial commitment of the US in the containment policy.