Final answer:
Money is a flow variable, while income is a stock variable.
Step-by-step explanation:
The correct statement is B) Money is a flow variable.
In economics, a flow variable refers to a quantity that is measured over a period of time. Money is considered a flow variable because it represents the rate at which currency is exchanged and used in the economy.
Income, on the other hand, is a stock variable because it measures the total amount of money earned or received during a specific period of time.