B. The united states began to build up its military and stockpile weapons. Both the US and the USSR participated in whats known as the arms race where the US collected enough atomic bombs to destroy the earth 25 times.
I would be happy to help if given more than information
I suppose it made the free states and slave states in some way even. When Missouri became a slave state they kept the north end of the Louisiana purchase free stated and banned slavery there.
I cant decide between B and D i think it might be B