C. It provided military support to countries fighting communism.
Explanation:
The Truman Doctrine undermined Soviet attempts to spread communism by providing military support to countries that were fighting off communism.
The Truman Doctrine came to light after the speech by President Harry Truman. The main goal was to "contain" communism, or stop the spread of it. The Truman Doctrine guaranteed that if a smaller country or another country was fighting off communism, troops would be sent to help fight it off.
People were very scared of communism during this time and saw communists as people without morals or respect, so it was really important to stop the spread of it and contain communism to prevent fear in the people.
