Which type of change-political, social, or economic-faced the most challenges? Why were Southerners against this type of change?

In the social change, slavery was the primary catalyst. The Southern protests against Northern attempt to prevent slavery from spreading into the west were a major catalyst for secession. There is also the possibility that southern nationalism played a role in secession and the subsequent formation of the Confederacy.

Explanation:

they thoght they were going to nuke each other