Answer:
C. prohibition of slavery within the territory and establishing the Ohio River as the border between free and slave states in the territory
Step-by-step explanation:
The Northwest Ordinance legalized the use important geographical features to separate 2 political regions in United States.
The Slave states are the states which legalize the use of slave labors in business organizations and private tasks.
The Free states make the use of slaves in any shape or forms become illegal.
The ordinance was important for the confederates states to create a distinction on which lands that they can sell to planation owners who wanted to expand their businesses. Plantation owners from southern states generally prefers to buy lands in the slaves states to increase their profit.