Which of the following allowed radical Republicans to take control of reconstruction policy?

A) Their leadership of the department of war

B) Their control of two-thirds of the house and senate

C) The removal of President Johnson from office

D) The withdrawal of the federal troops from the south

Members of the Congress called Radical Republicans vowed to take control of Reconstruction.

Republicans were able to take control of Reconstruction because they had a solid majority - southern Democrats couldn't vote and northern Democrats had lost credibility (they were considered to be pro-Confederacy or, at least, in favor of settling the war vs. winning it). They did so out of profound philosophical differences with President Andrew Johnson over treatment of the former Confederate states and the newly-freed slaves.