Answer:
1. Radical Republicans should amend the constitution, so as to nullify the Black Codes in the South.
2. Three possible things the Radical Republicans could do about violence against African Americans in the Confederate states right after the Civil War include;
a. Enact laws to designate as illegal the activities of the White supremacists.
b. Amend the constitution
c. Create awareness in the black community about their rights and privileges.
Explanation:
When the White masters realized that after the Civil War, they could no longer compel the Black Slaves to work for them, they enacted the Black Codes which greatly limited the Blacks. For example, under the Black Codes, they were not expected to work for more than one master. Slaves who violated any of the codes were made to work without pay.
Radical Republicans could challenge this by making an amendment to the constitution. They achieved this through the 14th amendment that recognized the rights of the slaves. They also enacted the Civil Rights Act. Creating awareness among the Blacks and encouraging them to report acts of injustice are ways the Radical Republicans could have helped the Blacks.