Answer:
C. the fact that for a barter trade to take place between two people, each person must want what the other one has
Explanation:
The double coincidence of wants is the foundation of barter trade and bartering economy. In order to avoid the usage of money as an exchange medium, both parties engaged in a barter must what the other one has.
If there is a discrepancy present, then a monetary medium has to be used in the exchange of goods or services.