Which reform provided the most direct benefit to daruis i's bureaucracy in the persian empire

The options of the question are:

A) common coinage made it easier to pay more taxes

B) the mail system enabled better communication among satrapies  

C) the standardized of weights and measures increased trade

D) the imposition of a state religion ensured a shared culture

The correct answer is D) the imposition of a state religion ensured a shared culture.

The reform that provided the most direct benefit to Darius I's bureaucracy in the Persian empire was the imposition of a state religion ensured a shared culture.

Emperor Darius was the ruler of the Persian Empire from 521-486 AD. His vast empire needed an effective form of control. So, he created a form of government centralized in Persepolis. He imposed a state religion and shared its culture in the territory. These helped to consolidate its power in the region.

Darius also used its Army to conquest the northwest part of India, Macedonia, and and part of the Black Sea region. These expansion of territory made Persia one of the largest and powerful empiures of the epoch.  

it's no easy i swear it's hard

the real answer is b