Baron de Montesquieu is most closely associated with which of the following ideas?

A-separation of powers

B-freedom of religion

C-the existence of natural rights

D-the social contract

I am pretty sure that Baron de Montesquieu is most closely associated with following idea : A-separation of powers. I consider this option to be correct because the thing that made his wellknown is his articulation of the theory of separation of powers, which means that this answer is definitely correct.