Which state was the first to secede from the union and on what grounds?

a. south Carolina: because it thought the federal government violated its obligation in states

b south Carolina-because they in acquired fort sumer

"South Carolina: because it thought the federal government violated its obligation in states" is the one state among the following choices given in the question that was the first to secede from the union. The correct option among all the options that are given in the question is the first option or option "a".