How did the Fugitive Slave Act increase tensions between the North and South?

A. It enraged Southerners because the North could harbor runaway slaves.
B. It increased the number of Slave States
C. It enraged Northerners because they were forced to catch runaway slaves and return them to the south.
D. It increased the number of Free States.

C. It enraged Northerners because they were forced to catch runaway slaves and return them to the south.