The northerners greatly disagreed with the act. The Fugitive Slave Act meant that if a slave ever escaped, he/she could be caught and returned to his/her owner. The northerners were primarily abolitionists, so they strongly disagreed with the Fugitive Slave Act.
The answer is B: Constitution.
No, Congress should not have the power to interpret the Constitution. The Constitution of the United States of America states that the legislative branch (including Congress) has the power to MAKE laws. The judicial branch (including the Supreme Court) has the power to INTERPRET laws. By giving the legislative branch the power to interpret the Constitution, you are giving it the powers of the judicial branch. This power must belong only to the judicial branch, NOT to the legislative branch or Congress. (NOTE: I'm not sure if this question is supposed to be a matter of opinion or not--if it is, this is my viewpoint.)
Let's see the answer choices:
Thaddeus Stevens - Yep! That's your answer, he was one of the Radical Republicans after the civil war!
Jefferson Davis - He was a democrat!
Abraham Lincoln - He was a lawyer.
Andrew Johnson - He wasn't a radical republican.
Have a nice day! :)