The Appalachian mountains because that was a border for them to prevent them from Basically going anywhere
Since there are no answer options under the question, the best answer is The Urban Areas
<span>The United States followed a policy of containment during the Cold War in response to the spread of communism. ... It authorized the use of military force againstcommunist forces in Vietnam. It provided economic aid to European countries inorder to prevent the spread of communism.</span>
It was "Fidel Castro" who <span>accepted Soviet aid for Cuba, since this was during the Cold War, and Cuba had recently become a communist country, much like the USSR. </span>
Fidel Castro based his government on Communism
