A fast-food restaurant accepts five dollars in cash as payment for three tacos. This is an example of money's role as a:

a. unit of account.

b. unit of coincidental want.

c. medium of exchange.

d. store of value.

The correct answer is c. medium of exchange.

Explanation:

Money is a financial asset that serves as an intermediate platform to optimize the exchange of goods and services, avoiding the inaccuracies of bartering, that is, the direct exchange of goods and services. Therefore, for a good to be qualified as money, the following three criteria must be met and that are the three main functions that money fulfills in a modern economic system:

Exchange medium: to avoid the inefficiencies of a barter system. When a good is required for the sole purpose of using it to be exchanged for other things, it owns this property. In addition, money should be a lightweight and easy to store and transport. Unit of account: When the value of a good is frequently used to measure and compare the value of other goods or when its value is used to denominate debts, it is said that the good possesses this property. The unit of account means that it is the unit of measure that is used in an economy to set prices. Conservation of value: When a good is acquired with the objective of preserving commercial value for future exchange, then it is said to be used as a store of value. Money is a store of value but not the only one, any asset that maintains its purchasing power over time will serve as a store of value.