In the 1850s the French franc was valued by both gold and silver, under the official French ratio which equated a gold franc to a silver franc 15½ times as heavy. At the same time, the gold from newly discovered mines in California poured into the market, depressing the value of gold. As a result, A. the franc effectively became a silver currency. B. the franc effectively became a gold currency. C. silver became overvalued under the French official ratio. D. answers a) and c) are correct