Answer:
D
Step-by-step explanation:
The Missouri Compromise was a disagreement between the South and North on whether or not to admit Maine and Missouri as free or slave states. They ultimately came to the agreement that if a state is below the 36th parallel, it would become a slave state and if above the 36th parallel it would become a free state.
This worked until further western expansion where the 36th parallel favored the North over the South.