The correct answer is A. The development of new consumer goods and the growth of commercial activity showed that the barter system was impractical.
To solve the problems of the barter system, men looked for a reference product to establish the values of all the goods based on that product. That reference is the first step in the history of the currency.
A coin is an element that serves to facilitate the exchanges. The first reference goods were wheat or cattle. Then it was possible to establish the price of the different products.
