Final answer:
John C. Calhoun and Daniel Webster disagreed on the issues of slavery and the power of the federal government, specifically related to the expansion of slavery into new territories and the nullification of federal laws.
Step-by-step explanation:
John C. Calhoun and Daniel Webster disagreed primarily on two major issues:
Slavery and the power of the federal government. Calhoun advocated for the South's right to extend slavery into newly acquired territories and for stronger enforcement of laws requiring the return of escaped enslaved people. He viewed the North's opposition to this expansion as an aggression that could lead to the South's demise and even proposed a dual presidency to represent the distinct interests of the North and South. Webster, on the other hand, championed national unity above sectional interests and opposed the dissolution of the Union over such issues. Additionally, Calhoun and Webster debated the legitimacy of Nullification, where states would have the right to invalidate federal laws they deemed unconstitutional, such as tariffs, which Calhoun supported but Webster opposed, insisting on maintaining federal supremacy.
The correct answer to the question is d. slavery and the size of the federal government.