Under the Gold Standard, Gold Flows Reduce the Money Supply

Under the gold standard, gold flows reduce the money supply in one nation when another nation experiences a trade surplus. The nation with a trade surplus has a swell in the money supply, which leads to price increases. At the same time, the nation with a reduction in the money supply will cause prices to fall. The lower prices create more demand for product from the nation with a reduction in the money supply, which leads to a

A) balance-of-trade.
B) facilitating payment.
C) tragedy of the commons.
D) floating exchange rate.
E) planned economy.