Final answer:
Money functions as a 'unit of account' when measuring the relative worth of goods or services, acting as a common denominator to simplify trade-offs.
Step-by-step explanation:
When money is used as a yardstick for measuring the relative worth of goods or services, it is functioning as a unit of account. This is one of the key functions of money in an economy, alongside being a medium of exchange, a store of value, and a standard of deferred payment. As a unit of account, money provides a standard measurement of value which simplifies trade and commerce. For instance, an accountant might charge $100 for a service, such as filing a tax return. This same $100 can be used to compare the value of other goods or services, like buying two pairs of shoes worth $50 each. In this role, money acts as a common denominator and an accounting method that makes it easier for individuals and businesses to understand the trade-offs and value of different goods and services.