What Did the Framers Do to Avoid the Executive Branch

What did the Framers do to avoid the executive branch from becoming a monarchy?

A) They made the president directly elected by the people.
B) They originally decided that the president should be elected by Congress.
C) They included separation of powers in the Constitution.
D) They did not allow the president to have military responsibility.
E) They limited the number of terms a president can serve.