The Anchor Currency in the Bretton Woods System Was the US

The anchor currency in the Bretton Woods System was the US dollar. What did this mean?

A) The dollar was convertible into any other currency at varying rates, but within a fixed range.
B) The dollar was fully convertible into gold at a fixed price, while other currencies in the system had a stable exchange rate with the dollar.
C) The dollar was fully convertible into gold at a fixed price, but other currencies in the system had variable exchange rates with the dollar.
D) The dollar was convertible into gold but at varying rates, depending on the state of the US economy.