When ricky sells his used desk for $50, money is a
medium of exchange
store of value
unit of account

The answer is the first option. When Ricky sells his used desk for $50, money is a medium of exchange. As you can see, money permits that Ricky gets rid of his desk (because he prefers the $50 dollars, likely to perform other purcahse) while the purchaser of the desk prefers the used desk over the $50 (likely because he needed a desk and did not want to spend more than $50). In this way, the money permits that one purchases the product that he wanted (the used desk) and permits that Ricky has money to purchase othet object that he wants.

Where are the options ?