The passage supports Kennedy's argument by drawing a connection between the domestic issue of slavery in the United States and the global issue of freedom versus oppression in the world. Kennedy is suggesting that just as the United States had to address the issue of slavery to ensure its own survival as a half-slave or half-free nation, the world must address the issue of freedom versus oppression to ensure its own survival as a half-slave or half-free world. Therefore, the correct response is: It draws a connection between domestic affairs and international affairs.