The roman empire was able to expand through

The Julio-Claudian dynasty came to an end with the murder of Claudius's deranged successor, Nero, in AD 68. The following year of dynastic struggle has been graphically named "the year of the four Emperors". From the turmoil emerged the able Vespasian, first of the Flavian Emperors. He and his sons Titus and Domitian ruled successively until 96, and maintained the empire. New territory was added in Germany, east of the Rhine, and the eastern frontiers were greatly improved and strengthened. The empire was not, however, to grow for much longer: forces were at work, both internally and externally, which were to bring about the protracted end of the Roman Empire.

the correct answers are 1, 2 5, 6