The correct answer is false.
It is false that this is an example of common knowledge: although he had previously been focused on domestic issues, as president, Truman led the United States as it took a leading role on the international stage with the founding of the United Nations, the Marshall Plan to rebuild Europe, and the Truman Doctrine to contain Communism.
What happens is that most people identify President Truman as the one who ordered the launching of the atomic bombs over Hiroshima and Nagasaki to end World War II, in what is considered one of the most controversial decisions of all times. Fewer people know that Truman also supported the creation of the United Nations, although previous President Franklin D. Roosevelt had so much to do with that.