What was the most beneficial reform that darius i made in the persian empire?

The most beneficial reform the Darius 1 made in the Persian Empire was building projects and administrative changes.

the indians crossed artificial boundaries, setting the stage for conflict

during the 20th century, the role of the vice president has evolved into more of an executive branch position. now, the vice president is usually seen as an integral part of a president's administration and presides over the senate only on ceremonial occasions or when a tie-breaking vote may be needed.