Answer - C: A line was drawn through the Louisiana Territory: territories north of the line except Missouri would be free; everything south of the line would be open to slavery.
Explanation - Missouri Compromise of 1820 was a solution to the disagreement between Northern and Southern states over slavery. It drew a line through the Louisiana Territory, with states north of the line being free and states south of the line, allowing slavery. This compromise allowed Missouri to enter as a slave state while maintaining a balance of free and slave states. However, it did not abolish slavery entirely and contributed to the growing tensions that led to the Civil War.