The true statement about money from the options provided is:
Money maintains purchasing power over time.
This statement is accurate in the sense that money is intended to serve as a medium of exchange and a store of value, although in practice, inflation and other factors can affect its purchasing power over time.
The other statements are false because:
- Money does provide a standard unit of measurement (it is used to value goods and services).
- Money does not stay at the same value over time due to inflation and other economic factors.
- Money does not retain the same value permanently, as its value can fluctuate.