Which One of the Following Is the Best Definition of Eurocurrency

Which one of the following is the best definition of Eurocurrency?

A) Any paper money used by a country that has adopted the euro as its common currency
B) Money deposited in a financial institution outside of the country whose currency is involved
C) Both paper and coins officially adopted under the euro system of coinage
D) U.S. dollars owned by any country which has adopted the euro as its currency
E) Any exchange of funds between two countries that have adopted the euro as their official currency