Which answer matches this clue: the 31 BC naval battle where Octavian's fleet decisively defeated Mark Antony and Cleopatra?

• A Battle of Naulochus
• B Battle of Actium ✓
• C Battle of Mylae
• D Battle of Pharsalus

Octavian's victory at Actium ended the civil wars and left him as sole ruler of the Roman world, soon to become the first emperor Augustus.