Answer:
C)White southerners believed allowing former slaves to attend school would threaten society.
Explanation:
The reason some of the schools might have been in danger of closing during the mid to late 1800s would be that white Southerners were against former slaves attending schools with their children because they believed it would threaten society.
They held this belief that they were superior to the former slaves, of which majority of them were blacks so they did not want them interacting with their children.