The correct answer is D) The failure of African Americans to organize politically and take advantage of their right to vote.
Congressional Reconstruction was undermined and abandoned as a result of all of the following developments except: "The failure of African Americans to organize politically and take advantage of their right to vote."
In that time, African Americans did not have the right to vote. They were slaves in the southern states that worked in the owners' plantations producing cash crops such as cotton.
President Abraham Lincoln aimed for a quick Reconstruction process and to integrate all of the Confederate States into the Union. So he gave leeway to the Southern States to work on its own reconstruction process and just demanded that 10% of people in each state declared loyalty to the Union to be accepted. Of course, Radical Republicans in Congres did not like the idea and heavily opposed to Lincoln's plan.
