Why would the spread of communism cause concern for the United States?

The United States felt threatened by the spread of communism because free enterprise and the capitalist system was the basis for American economy and, therefore, the American way of life.

i really really really really really really dont know

no statements but ok.

the statement that best describes the idea of manifest destiny that was used in the 19th century would be that "it was fate that the united states would continue to  expand westward," since people thought the us was "destined" to do so.