12. the process by which the federal reserve controls the supply, availability, and cost of money in order to keep the economy stable is

The correct answer is: "the monetary policy"

The monetary policy is the mechanism through which a central bank, such as the US Federal Reserve, is able to indirectly influence the economic output and its growth trends, by changing the amount of money in circulation in the economy, the so-called money supply.

The are several instruments that the monetary authorities can use to modify the money supply levels: changing the interest rate, modifying the mandatory coefficient of reserves of the banking system, purchasing or selling public debt, etc.

an earnest tone.

because portia wants to know why brutus has been acting strange lately.