Final answer:
The example of the price of a dozen roses set at $50 exemplifies the unit of account function of money.
Step-by-step explanation:
The function of money as a unit of account is exemplified by the choice where the price of a dozen roses is set at $50. This represents how money is used to provide a specific value to goods or services, making transactions easier to carry out by valuing these goods using a single, common currency.
The unit of account function allows for items to be compared and priced, thus facilitating the process of trade by providing a common measure of their worth.