Which action contributed to the Southern belief that their economy was threatened? a. The founding of the Republican party
b. The finalization of the Missouri Compromise
c. The support of popular sovereignty in territories
d. The approval of protective tariffs on manufactured goods

D. The approval of protective tariffs on manufactured goods.

Explanation:

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The North developed economically much more than the South in the first half of the 19th century. Slavery was quickly abolished and the economy reverted to the rising industry to such an extent that during the Civil War about 80% of the industry in the USA was in the North.

Explanation: