Which statement summarizes how the Roman Empire formed?

A. The Roman Empire formed due to the first civil war and the death of Caesar, which made Octavian the first emperor of Roman
B. The Roman Empire formed due to the conflict among the First Triumvirate that made Octavian the first emperor of Rome
C. The Roman Empire formed when Octavian defeated Antony at the Battle of Actium, making Octavian the first emperor of Rome
D. The Roman Empire formed due to the march over the Rubicon river, which made Octavian the first emperor of Rome