The primary argument used by president abraham lincoln against the secession of southern states during the civil war was a) the virginia and kentucky resolutions did not allow for slavery to exist. b) the union was a union of people, not of states, so secession was impossible. c) secession was unconstitutional under the fifth amendment to the u. s. constitution. d) the 10th amendment to the constitution, as applied through the necessary and proper clause, made such actions unconstitutional.