Under the gold standard of currency exchange that existed from 1879 to 1914, an ounce of gold cost $20.67 in U.S. dollars and 4.2474 in British pounds. Therefore, the exchange rate of pounds per dollar under this fixed exchange regime was:

A. unknown because there is not enough information to answer this question. B. always changing because the price of gold was always changing. C. 0.2055/$. D. 4.8665/$.