The correct answer is B.
The 13th amendment to the US Constitution abolished slavery in the states where it still existed. Meanwhile, the 14th and 15th amendments to the US Constitution guaranteed citizenship for former slaves and equality of rights for all US citizens without discrimination in terms of race.
State law did not ratify those provisions, and the best example are the Jim Crow Laws, enacted at the state level in order to block the access to voting to black citizens. These laws could not exclude black citizens explicitly but, instead, they introduced requirements for voting that in the end ruled out mostly black citizens, such as a minimum income level or literacy tests. The ultimate aim of such laws was to prevent black citizens from voting this is why, after a while, the Supreme Court ended up abolishing them. But as soon as one law was abolished, a new one was ready.
The enforcement of the equality of rights in voting included in the reconstruction amendments, would not be materialized until 1965 with the enactment of the Voting Rights Act (VRA).