Could you help me this question:

1/ A "double coincidence of wants" occurs when

a.

a/ third party to an exchange transaction has what both other parties desire.

b/ the negotiation between parties arrives at a mutually accepted medium of exchange

c/ each party in an exchange transaction happens to have what the other party desires

d/.each party in an exchange transaction fails to have what the other party desires

e/ both parties in an exchange transaction have a sufficient quantity of the medium of exchange.