A National Monetary System Represents a Public Good Because

A national monetary system represents a public good because:

A) it is easy to exclude people from using a currency.
B) it only has benefits for a minority of people who buy and sell goods internationally.
C) there are no downsides to providing a national currency.
D) people cannot be excluded from the monetary system or charged for using it.
E) multiple actors in the international system would like control over the monetary supply and only one actor should have it.