When the Central Bank Wants to Reduce the Monetary Base

When the central bank wants to reduce the monetary base,

A) it buys short-term government bonds and accepts as payment either currency or deposits that banks already hold at the Fed's regional branches.
B) it sells short-term government bonds and accepts as payment either currency or deposits that banks already hold at the Fed's regional branches.
C) it buys back government bonds to reduce government debt.
D) it raises taxes.