What was the significance of the achaemenid use of a coin-based money system?

Although Darius I presented a gold daric weighing 8.42 gm, which shaped the basis for the Achaemenid monetary system, as well as the silver shekel with a weight of 5.6 gm., these coins were little used external Asia Minor. In Persia itself coins were not in movement. Workmen in the salary of the royal sector, and even the highest officials, were compensated their salaries in unminted silver and products in kind. Such exercise is also showed to in documents from Babylonia and Egypt of the Achaemenid period. In common, the Persians used coins for marketable exchange with the Greeks along the borders of the state and for payment to salaried mercenaries, especially in Asia Minor. In countries situated beyond the Mediterranean (e.g., Babylonia), internal trade payments were made in ingots of silver. When coins came into circulation, they were also accepted by weight as unminted metal. Also, it helped a lot with taxes and banking. Croesus created this system. This made their economy a lot better than others.

The correct answer is "c) beginning inventory for the first quarter"