Many radical republicans had been abolitionists before civil war

After the Civil War, and Lincoln's assassination, the Radical Republicans were outraged by the policies of President Andrew Johnson. Opposition to Johnson included overriding presidential vetoes of legislation and eventually organizing his impeachment.

Background of the Radical Republicans

The leadership of the Radical Republicans tended to be drawn from the abolitionist movement.

Thaddeus Stevens, the leader of the group in the House of Representatives, had been an opponent of slavery for decades. As a lawyer in Pennsylvania, he had defended fugitive slaves. In the U.S. Congress, he became head of the very powerful House Ways and Means Committee and was able to exert influence on the conduct of the Civil War.

b. parliament was weaker than the monarchy.

the answer would be:

b. race