Final answer:
Sectionalism in the United States was deeply affected by the Denmark Vesey Plot and the abolitionist movement, both of which heightened tensions and fears, contributing to the division between the North and South that led to the Civil War. The correct option is D.
Step-by-step explanation:
Sectionalism in the United States was significantly influenced by both the Denmark Vesey Plot and the abolitionist movement. The Denmark Vesey Plot of 1822 unveiled the deep-seated fear and tension surrounding the notion of slave rebellion in the South, leading to stricter slave codes and heightened distrust between the North and South.
The abolitionist movement, spearheaded by figures like William Lloyd Garrison, continued to create a rift as it became more radical and vocal over time, with actions such as John Brown's raid on Harper's Ferry intensifying the divide. As such, sectionalism was not an isolated phenomenon but rather was exacerbated by both the fears ignited by the Vesey Plot and the sustained ideological and moral battle waged by abolitionists against slavery.
Conclusion: The sectionalist discord, with roots in divergent economic and social systems, was further deepened by fears of slave insurrection and the moral crusades of anti-slavery activists. The differing perspectives on slavery's morality and legality only intensified the nation's division into largely sectional lines of pro-slavery South and anti-slavery North, ultimately leading to the Civil War.