During the reign of Darius I, the Persian Empire was reorganized politically. The empire was divided into 20 provinces with local governors, roads were built to keep it connected, and a mail system was created.

How did the reforms mentioned above help the Persian Empire?
A.
They helped create a more democratic government.
B.
They helped to make peace with foreign enemies.
C.
They helped gain more money from taxation.
D.
They helped keep the large empire united.