Answer:
the Feds.
Step-by-step explanation:
The Fed controls the money supply with three primary tools: open-market operations, the discount rate, and reserve requirements. The Fed—or a central bank—influences the money supply and interest rates by purchasing and selling government assets (typically bonds).
In other words...Three methods are used by the Federal Reserve System to control the money supply. They are: Reserve to income ratios Banks are obligated to keep a percentage of their deposits as a "reserve" against possible withdrawals. The Fed manages the amount of money in circulation by adjusting this amount, known as the reserve ratio.
Central banks work hard to keep a country's economy healthy. One method central banks achieve this goal is through managing the amount of money in the economy.