6) What does Dr. King call the "greatest stumbling block" to African American civil rights.

pan-africanism or pan-africanism is a political, philosophical, cultural and social movement that promotes african twinning, the defense of the rights of african people and the unity of africa under a single sovereign state, for all africans, both africa as of the african diasporas.

because their parents smoke while in labor

i would say the executive branch is because the executive branch is in charge of enforcing the laws and judicial branch is in charge of enforcing but the executive branch is most responsible for it all so i would have to say the executive branch.