In the Context of Monetary Barriers, Blockage Is Ideally Accomplished

In the context of monetary barriers, blockage is ideally accomplished when

A) a country refuses to allow an importer to exchange its national currency for the country's currency.
B) two countries enter into a voluntary agreement to determine the value of their currencies.
C) a country applies a specific unit or dollar limit to a particular type of good.
D) money dealers limit the rate at which foreign currencies are exchanged.
E) the government of a country imposes a mandatory tax on goods entering at its borders.