Under a Fixed-Rate Unified Currency Regime, Each Country Belonging to the System

Under a fixed-rate unified currency regime, each country belonging to the system

A) may pursue an independent monetary policy.
B) gives up its monetary policy independence to one central bank with the power to expand and contract the money supply.
C) is committed to conducting highly expansionary monetary policy in order to maintain the convertibility of its currency.
D) must fix its domestic interest rates in order to maintain the convertibility of its currency.