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.
During the 1858 senatorial campaign in Illinois, there was a series of 7 debates between the Republican Lincoln and the Democrat Douglas. They were mainly about the extension of slavery into the territories.
Question: What were the key issues in the Lincoln-Douglas debates?
Answer: Lincoln did not want to see slavery expand. Douglas believed in popular sovereignty.
Wait so what is the question