$9$A problem that the Fed faces when it attempts to control the money supply is that$1$the Fed must get the approval of the U$.$S$.$ Treasury Department whenever it uses any of its monetary policy tools$\mathrm{.}2$while the Fed can change the money supply by a large amount, it does not have the ability to change it by a small amount$\mathrm{.}3$the amount of money in the economy depends in part on the behavior of depositors and bankers.