C - Southerners feared it would lead to the end of slavery
One way in which Americans developed a unique cultural identity after the Revolution was by ratifying the Constitution, which created a true "nation" as opposed to a lose confederation of states, which allowed people to develop a sense of nationalism and "pride" in their country.
This is a general response. The connection between workers and industrial capitalists is more freeing than the one between workers and landowners. The latter might keep memories of servitude alive (and in this case racial discrimination). Additionally, the broader economic shift throughout time has been caused by mechanization in agriculture, which uses fewer employees. These surplus workers then relocate to cities to work in the industrial and service sectors.
Thank you,
Eddie