Answer:
The Fed can increase the monetary base using one of these two tools:
- Open-market operations: if the Fed wants to increase the money supply, it can buy government bonds. The money the Fed prints to buy these bonds increase the monetary base.
- Reserve requirements: the Fed can increase the reserve-deposit ratio for commercial banks. In other words, commercial banks will have to keep more reserves as a percentage of the deposits they hold, and this increases the monetary base.