Answer: B is correct.
Explanation: there were many who wanted to follow isolationism arguing that the war was problem of Europeans, there were also those (many Americans were of European origin with their roots in different corners of the Old continent). Situation changed and USA (country of European origin and roots) entered the war and continued engaged in (especially) European security policy.
Answer:
Europeans explored and claimed that more and more land was there. They had to make relations with people who were already in the Americas and try to find a way to conquer them and claim that land theirs.
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