Why did northern states oppose the Fugitive Slave Act?

A. The Fugitive Slave Act forced people in northern states to allow slavery in the new territories.

B. The Fugitive Slave Act forced people in northern states to return escaped enslaved people to their enslavers.

C. The Fugitive Slave Act forced people in northern states to allow slavery to continue in their states.

D. The Fugitive Slave Act forced people in northern states to allow the slave trade to continue in Washington, D.C.