What Is a Fixed Exchange Rate

What is a fixed exchange rate?

A) A trading system in which governments do not limit how many goods can be sent between countries
B) A monetary system in which the exchange rates of currencies are set at a permanent price of another currency or a precious metal
C) A monetary system in which the exchange rates of major currencies retain nearly the same value with respect to gold but are periodically adjusted in response to currency crises
D) A monetary system in which exchange rates are allowed to change according to their market price