Which of the following describes the difference between the fiscal deficit and the national debt? A) The national debt is owed to foreigners while the fiscal deficit is owed to domestic residents. B) The national debt is a stock concept while the fiscal deficit is a flow concept. C) The national debt is smaller than the fiscal deficit. D) The national debt is financed by Treasury bill sales while the fiscal deficit is financed by Treasury bond sales.

The correct option describing the difference between the fiscal deficit and the national debt is:

B) The national debt is a stock concept while the fiscal deficit is a flow concept.

In economics, a stock refers to a measure of value at a specific point in time (i.e., the amount owed at a moment), while a flow refers to a measure observed over an interval of time (i.e., how much is borrowed each year). The national debt is the total amount of money that a government has borrowed and not yet repaid. It is a stock concept because it represents the total outstanding debt at a point in time. On the other hand, the fiscal deficit is the difference between the government's spending and its revenues within a specific period, usually a year. It is a flow concept because it indicates the amount of borrowing that has occurred within a specified time frame.

Therefore, option B is the correct description of the difference between the fiscal deficit and the national debt.

\textbf{Answer: } B