The Gold Standard Was a _______ Exchange Rate System Because

The gold standard was a _______ exchange rate system because

A) floating; each government would define a unit of its currency as worth a certain amount of gold and buy or sell its currency for gold at that price at any time.
B) fixed; each government would define a unit of its currency as worth a certain amount of gold and buy or sell its currency for gold at that price at any time.
C) fixed; each government would define a unit of its currency as worth a certain amount of gold, but would only buy or sell its currency for gold at that price if it was profitable to do so.
D) floating; each government would define a unit of its currency as worth a certain amount of gold, but would only buy or sell its currency for gold at that price if it was profitable to do so.