What inspired john c. calhoun's theory of nullification?
a) a threat by president jackson to end the institution of slavery
b) the election of john quincy adams
c) john brown's raid on harper's ferry
d) the passing of the tariff of 1828

D) the passing of the Tariff of 1828

Explanation:

"Calhoun openly argued for a state's right to secede from the Union, as a last resort to protect its liberty and sovereignty. In his later years, Madison rebuked supporters of nullification, stating that no state had the right to nullify federal law. "

Source: https://en.wikipedia.org/wiki/John_C._Calhoun

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