Final answer:
Sectionalism led to the secession of Southern States due to a combination of economic disparities, cultural differences, and slavery-related tensions. The Southern reliance on slavery for agriculture and the North's opposition to it created an economic and ideological divide that grew until secession appeared to be the South's only option.
Step-by-step explanation:
Sectionalism and the Path to Secession
The increase in sectionalism that eventually led to the Southern States seceding from the United States, or the Union, can be attributed to d) All of the above: Economic disparities, cultural differences, and slavery-related tensions.
The Southern economy was heavily dependent on slavery for the production of key crops like cotton and tobacco, creating a stark economic disparity between the North and South. Northerners, who did not rely on slave labor for economic success, supported tariffs and federal measures that Southerners believed threatened their plantation economy and the institution of slavery. Culturally, the North and South developed distinct identities, with differing views on the role of the federal government and the expansion of slavery into new territories.
Ultimately, these compounded tensions over economics, culture, and the institution of slavery made secession seem the only resolution to Southern States who felt their way of life and economic interests were under direct threat by Northern policies and abolitionist sentiment.