In Terms of Exchange Rates, What Was the Initial Purpose

In terms of exchange rates, what was the initial purpose of the Bretton Woods system?  

A)  Foreign currencies could be converted into U.S. dollars, which could be redeemed for gold at a rate determined by supply and demand. 
B)  Foreign currencies could be converted into U.S. dollars, which could be redeemed for gold at a rate of $35 per ounce. 
C)  Foreign currencies could be converted into gold at a rate determined by supply and demand. 
D)  Foreign currencies could be converted into gold at a rate of $35 per ounce.