Final answer:
The council for economic mutual assistance set up by Moscow in 1949 to rival the U.S. aid to Europe was the Council for Mutual Economic Assistance (COMECON).
Step-by-step explanation:
The council for economic mutual assistance set up by Moscow in 1949 to rival the U.S. aid to Europe was the Council for Mutual Economic Assistance (COMECON). This organization provided economic aid to its member nations in Eastern Europe, despite the relative weakness of the Soviet economy.
The Marshall Plan, on the other hand, was the U.S. program that provided economic aid to European nations, including the Soviet Union, to help them rebuild their economies after World War II. The goal of the Marshall Plan was to prevent the spread of communism by promoting economic stability and democracy in Europe.
Therefore, the correct answer is b) Marshall Plan.