The capital city of the Roman Empire was officially moved from Rome to the ancient Greek city of Byzantium in 330 CE.

The city was renamed to Constantinople in honor of emperor Constantine I (the Great).

The correct answer is "tetrarchy." A tetrarchy is a form of government that is split between four different heads of government. The key here is the concept of decentralizing power. The other forms of government put the power in one person's hands, unlike a tetrarchy. This move by Diocletian ended the crisis of the third century.