Answer:
It serves as a medium of exchange.
Step-by-step explanation:
It serves as a medium of exchange is the correct answer because in the trade money plays an important role and it makes the trading very easy as compared to barter system where a person has to find the other person who is in the need of same commodity through which the other person wants to exchange. Moreover, the use of money as a medium of exchange eliminated all the problems that were in the barter system.