A Currency Board Arrangement for Managing the Value of a Country's

A currency board arrangement for managing the value of a country's currency occurs when

A) The country's currency can be exchanged at a fixed rate into a foreign money unit (such as the euro or dollar) and is backed with sufficient foreign currency reserves to cover requested changes.
B) The country uses a managed float to set the exchange rate for its currency but does not reveal the target rate set by the currency board of the central bank.
C) The central bank of a country pegs the value of the currency to some other money unit but allows it to deviate a small amount (such as ?1%) , but which requires explicit approval from a designated committee, called the currency board, to reset the central rate around which the deviations are measured.
D) Withdraws its own currency from circulation and uses the money unit of another country as its official currency.
E) None of the statements above.