What was one of the main points of conflict surrounding the Kansas-Nebraska Act?

The correct choice highlights a central issue of the Kansas-Nebraska Act, which was the application of popular sovereignty in determining the status of slavery in the new territories of Kansas and Nebraska. The Act, passed in 1854, explicitly allowed the settlers in each territory to decide for themselves whether to permit slavery or not, effectively nullifying the Missouri Compromise that had previously established a boundary between free and slave states.

This legislation ignited intense conflict because it reopened the contentious debate over the expansion of slavery into the western territories. Pro-slavery and anti-slavery factions both moved to Kansas, leading to violent clashes known as "Bleeding Kansas." The principle of popular sovereignty was controversial; it raised questions about the morality and practicality of allowing local decision-making on such a divisive issue.

Understanding this context is crucial because it underscores how the Kansas-Nebraska Act was not only about regulating slavery but also about the broader implications of self-determination and governance in American territories during a period of increasing sectional tension.