The correct answer is D) all of the above.
Merchants decided to use money instead of bartering because money was easier to carry and handle than goods, money was accepted anywhere and could be used again, it was difficult to exchange the exact value of goods in barter.
Merchants realized that there were many benefits to changing to the monetary system when trading their goods. The reasons mentioned above were enough to opt for money instead of bartering. They considered this new system to be fairer in that money represented more equity in trading than in bartering because some times the value of things exchanged was not the same.