Jim Crow laws were any of the laws that enforced racial segregation in the American South between the end of Reconstruction in 1877 and the beginning of the civil rights movement in the 1950s.
Choice A is wrong because only 26 presidents have served in the military. Choice B is wrong because not all presidents have been governors. Choice D is wrong since James Buchanan and Grover Cleveland were not married. Therefore, Choice C is the correct answer.