People thought slavery would end because revolutionary idealism went against it and many leaders spoke about freeing their slaves. Others thought that economics would kill it because it was unprofitable. The invention of the cotton gin saved slavery.
The Fourteenth Amendment later became the basis for equal rights claims.
I think the answer is A surplus
Improve society and address economic problems
(C.) Edwin Hubble discovered that there were other galaxies besides the Milky Way.
Check out page 869 in the Glencoe Earth Science textbook provided by PennFoster. The answers are on there :)