Which best explains how the Kansas-Nebraska Act affected the Missouri Compromise? 
It strengthened the Missouri Compromise by prohibiting slavery in states above the 36°30’ N line.It overturned the Missouri Compromise by requiring slavery in states below the 36°30’ N line.It overturned the Missouri Compromise by allowing the possibility of slavery in states above the 36°30’ N line.It weakened the Missouri Compromise by allowing the possibility of slavery in states below the 36°30’ N line.

 C. 
It overturned the Missouri Compromise by allowing the possibility of slavery in states above the 36°30’ N line.