The correct answer is A. To emphasize the persistence of racism.
Indeed, his descriptions of slavery were used to demonstrate several things; but the most important were that racism was a byproduct of slavery, and that it sought to perpetuate it though other forms of oppression. A recurrent argument of Southern white supremacists was that since slavery was over, African Americans now enjoyed equal rights and that segregation ensured such “freedom”. By reminding his followers and listeners that slavery was still perpetuated by the subjugation, segregation and imprisonment of African Americans.