The cotton gin made it easy for slaves to separate seeds out of the cotton. However, it it increased slave usage all over. It actually increased the use of slavery. The cotton gin just made one part of a slaves job quicker and easier.
I believe that the United States had no imperialistic motives for entering WWII. Because Great Britain, Russia, and Germany all used to be empires at some point in their history, and they might have wanted to become empires again, whereas America had no such wishes.
The correct encapsulation of today's divide between Republicans and Democrats is: C. Republicans believe in small national government while Democrats believe in large national government