Answer:
Popular sovereignty
Step-by-step explanation:
Kansas Nebraska Act was proposed by Stephen Douglas and became a bill in 1854 after signed by President Franklin Pierce. Aiming to build a transcontinental road, it needed the support of southern allies and therefore it breach the Missouri Compromise of 1850 by which the pro-slavery territories are separated by anti-slavery territories by the latitude north of the 36°30′. The act allowed the settlers to decide on the issue of slavery through popular sovereignty and it resulted in Bleeding Kansas and later Civil war.