The correct answer is D.
In the United States, after the enactment of the Reconstruction Amendments (after the Civil War), which guaranteed equality of rights for all US citizens, many Southern states tried to circumvent such provisions with the enactment of the so-called Jim Crow laws. These legal instruments were based on the "separate but equal lemma" which stated that, if the facilities were equal in quality, the equal-rights provision was being respected. Hence, Jim Crow laws constituted the legal base that allowed segregation to occur.