The correct option is C
Slavery was practiced in British America from the beginning of the colonial era, and was firmly established when the Declaration of Independence of the United States was signed. After this, there was a gradual expansion of abolitionism in the North, while the rapid expansion of the cotton industry since 1800 caused the South to cling tightly to slavery, and try to expand it into the new western territories of the country. Thus, slavery polarized the nation into slave states and free states through the Mason-Dixon line, which separated Maryland and Delaware (slavers) and Pennsylvania (free).
