The correct answer is B. Roman empire.
Diocletian was a Roman emperor. He enlarged and separated military empire and civil empires.
He later reorganized division for those empires which was bureaucratic and largest in the government for history of empire.
There was increase in tax reform because construction projects, constant campaigning and military growth.
There are other plans which Diocletian had but they were ignored. For example, he wanted to curb inflation through price control which was edict on maximum prices.