Answer:
Their economies were based on different principles and systems, is the right answer.
Step-by-step explanation:
There were a number of factors that were responsible for the tensions between the U.S. and the USSR after World War II. Some of the factors include the extreme distrust, the spread of communism, the destruction of capitalism by the Soviet Union etc. However, the most important factor responsible for tension between the U.S. and the USSR after the Second World War was that the economies were based on different principles and systems. These factors were strong enough to create a war-like situation between the two.