Question

the formation of the united nations was a response to the post - war desire for international cooperation. the truman doctrine, which tried to contain communism. the creation of the marshall plan to help rebuild europe. the formation of the defense organization nato.

Explanation:

The United Nations was established in 1945 after World War II as countries sought international cooperation to maintain peace and security, and promote social progress and better living standards. The other options are related to aspects of the Cold - War era and not the main reason for the UN's formation.

Answer:

the post-war desire for international cooperation.