The "Doctrine of the Separation of Powers Was Adopted by the Convention

The "doctrine of the separation of powers was adopted by the Convention of 1787, not to promote efficiency, but to preclude the exercise of arbitrary power." This statement meant that:

A) A certain amount of governmental friction is needed among the three branches of government.
B) Government efficiency is not the primary need in a democracy
C) A and b
D) None of the above