What government action prohibited slavery in the territories north of the Ohio River after the American Revolution?
A) the Missouri Compromise
B) the Articles of Confederation
C) the Emancipation Proclamation
D) the Northwest Ordinance of 1787

the answer is the northwest ordinance of 1787

Explanation:

The Northwest Ordinance (formally An Ordinance for the Government of the Territory of the United States, North-West of the River Ohio, and also known as The Ordinance of 1787) enacted July 13, 1787, was an organic act of the Congress of the Confederation of the United States.

the answer is a glaciers carved a large valley that later flooded and became puget sound