Which of the Following Helped Augustus's Transformation of Roman Government

Which of the following helped Augustus's transformation of Roman government become permanent?

A) His reign of forty-one years was so long that by his death very few Romans had a firsthand memory of the old republic.
B) His extensive military conquests later in life allowed him to distribute the spoils of war to his army and to the citizens of Rome, thereby ensuring acceptance of his new system.
C) He abolished the hallmark institutions of the republic, including the assemblies, the consulships, the tribunes, and the Senate.
D) His heavy reliance on brute military force and his extravagant demeanor allowed him to terrify not only his political opponents but also the entire population into submission.