What is a system of government where power is constitutionally divided between a central governing body and various constituent units?

The government system that has power constitutionally divided between various constituent units an the central government is called federalism. Federalism is really just a mix of lots of different types of government. It combines the general type government with smaller regional governments, but they all work together to make a big political system.

The answer is d.  the north had organized schools, whereas the south had few organized schools.