The American attitude shifted in favor of rights for Native Americans. This is based on "Polls showed that Americans believed in rights for Native Americans". Why it's not B is because it wasn't the polling that contributed to the act, but what the polls showed which is C.
Answer: The tariff helped to increase Nationalism and helped the economy because it protected American goods of foreign competition and the US could buy cheaper products.
Checks and balances? that might not be right i’m not sure
During the Cultural Revolution, bourgeois intellectual were sent to re-education camps to be taught in a communist ideology. Many of them were teachers and professors in charge of the education of the common people. But their ideology didn't match the communist one, so they were sent to these camps to be taught how was like to be a peasant or a common person who had to work hard to survive. This movement despised intellectual labor and valued hand labor.