Which function allows money to be used to make purchases

The function that allows money to be used to make purchases is unit of account.

Explanation:

There are four functions of money namely; a unit of account, a store of value, a medium of exchange and a standard of differed payments. Money is a unit of account because it can be used to determine the value of goods and services. Using money will allow buyers and sellers make purchases and sales independently. A unit of account is divisible, fungible and countable.