In the Early Part of the Twentieth Century, Nearly All

In the early part of the twentieth century, nearly all currencies

A) were backed by gold.
B) were held together by a system of fixed exchange rates in which the value of those currencies was set in relation to the British pound.
C) were held together by a system of fixed exchange rates in which the value of those currencies was set in relation to the U.S. dollar.
D) were held together by a system of flexible exchange rates in which the value of those currencies fluctuated in response to the relative supply of and demand for them.