Under the Bretton Woods Agreement, If a Country Other Than

Under the Bretton Woods agreement, if a country other than the United States ran a trade deficit, downward pressure was exerted on the currency's exchange rate. In order to maintain the agreed-upon exchange rate, what must this foreign central bank do?

A) It must purchase the excess supply of dollars with its own currency.
B) It must purchase the excess supply of its own currency with dollars.
C) It must supply its own currency and demand dollars to create a surplus in the official reserve account that just equals its deficit on current and capital accounts.
D) Both b and c