The correct answer is money
In simple terms, we can say that the real flow is all that families use for companies that may exist, for example: natural resources, labor, labor and entrepreneurial capacity. In the same order, as companies that receive these families they need to maintain, for example: industrialized products, jobs.
With the aid of money, as companies pay families for the service and labor performed and, in turn, as families, also with the help of money, they pay companies for goods and services purchased, or that configure the cash flow.
The real and monetary flows make it possible for families and companies to interact, which they call economic agents. The real flow side is in the use of resources and the supply of necessary goods and services. The monetary side gives the remuneration of the factors of production and the payment of the goods and services purchased.
