Answer:The answer is the Ku Klux Klan (KKK).
Explanation: The radical republican's goal during the reconstruction era was to help African Americans achieve equality by guaranteeing their rights to vote in the south.
It can't be Northerners as they opposed slavery and the oppression of African Americans.
The Freedman's bureau actually helped slaves gain their freedom.
Out of all the choices only the Ku Klux Klan were for slavery and oppressing African Americans.