Answer: The group that worked to stop violence against African Americans among the options provided is:
B) The Radical Republicans
During the Reconstruction era in the United States (1865-1877), the Radical Republicans were a faction of the Republican Party who advocated for civil rights, voting rights, and equality for African Americans. They sought to protect the rights of African Americans and worked towards ending violence and discrimination against them, particularly in the Southern states where African Americans faced widespread oppression and violence during the period following the Civil War.
The Southern Democrats, on the other hand, were known for their opposition to civil rights and voting rights for African Americans during the Reconstruction era. The Red Shirts and the Knights of the White Camellia were paramilitary groups formed in the post-Reconstruction period in the Southern states, which were associated with white supremacist ideologies and worked to undermine the rights and freedoms of African Americans, often through violence and intimidation.