Answer: b. can be used to purchase approximately the same amount of goods over time.
Step-by-step explanation:
There are several functions of money including that it is a store of value. This means that it can be used to exchange for goods that have the same value over a period of time. For instance, $5 for a $5 plate of food.
It also means that it can be saved such that the value that it has will allow for people to be able to exchange for goods in future. This can only happen if it keeps its value over the same period of time.