According to the video excerpt, which significant event marked the end of Cleopatra VII's reign and the independence of Ptolemaic Egypt in 30 BC?
A) Her marriage to Mark Antony.
B) The Battle of Actium against Octavian's forces.
C) Her formation of a powerful alliance with Julius Caesar.
D) Her death by suicide, leading to Roman annexation.
E) The successful defense of Alexandria against Roman attack.