Final answer:
Southern landowners were most likely to support Calhoun's views due to his defense of slavery and the plantation economy, his stance against high tariffs, and his concept of the concurrent majority to protect Southern interests.
Step-by-step explanation:
The correct option is A:
The group most likely to support Calhoun's views, given the historical context, would be a. Southern landowners. John C. Calhoun was a leading political theorist defending slavery and the rights of the South. As plantation economy was a prominent part of Southern life and Calhoun was strongly against high tariffs which would be detrimental to Southern interests, it's clear that his support base would have been primarily Southern landowners who benefited from the plantation economy and were pro-slavery. Southern landowners, who were heavily invested in the plantation economy and benefitted from slavery, would therefore be most likely to support Calhoun's views.
These landowners feared any federal interference as they believed it could lead to the disruption of their economic system and potentially threaten the institution of slavery. Thus, Calhoun's advocacy for states' rights and his stance against federal intrusion into economic and regional affairs resonated strongly with them. Calhoun's concept of a concurrent majority allowed a regional (Southern) minority to negate what they perceived as hostile legislation from the national majority, protecting their socio-economic interests.