Foreign Exchange Market Intervention Like Devaluation or Revaluation Occurs

Foreign exchange market intervention like devaluation or revaluation occurs

A) when a central bank changes interest rates.
B) whenever there is countercyclical fiscal policy.
C) only if a country has adopted a flexible exchange rate policy.
D) when a country's government buys or sells foreign currency to affect its exchange rate.
E) only when countries want to permanently alter exchange rates.