How did manifest destiny transform the united states from about 1835-1852, and how, in turn, did that transformation begin to divide americans, north from south?

Manifest destiny said that people with money and a higher power (such as the big companies at the time, oil, steel, etc.) were more superior than the inferior African American slaves. The north did not believe in manifest destiny, but the south wanted to keep their slaves and the tear began.

The answer should be b

What was the length to begin with?