The increase of slavery in the new Southwest during the antebellum era
A. created new tensions over the spread of slavery.
B. was firmly opposed by both major political parties.
C. led to the resumption of importing slaves from Africa.
D. decreased the market value of cotton and slaves in the East.
Answer: A
Explanation: The expansion and increase of slcaery in the new Southwest during the antebellum era created new tensions over the spread of slavery into the American territories in the 1850s. These tensions ultimately precipitated the Civil War.