Well in the 1850's was a significant time where slavery occurs. As you probably know slavery was terrible on so many levels. Becuase of the different opinions on slavery their political values changed., Some values thought that slavery was okay while the other fought against it saying that slavery should end. Different sections such as Indiana and Illinois has strong opinions to keep slavery including the south when the rest of America did not feel so strongly.
Because he was a president that supported limited government
The answer is (B) hydroelectricity
I just had a paper on this. here is a quote that is pretty useful
Mao believed that in focusing on the anti-imperialist struggle, the Communists would earn the trust of the Chinese people, who in turn would renounce the KMT. From Zunyi, Mao led his troops to Loushan Pass, where they faced armed opposition but successfully crossed the river.
hope this helped