Which of the following is an important reason why countries do not adopt the gold standard?

a. There is too much gold in the world right now to make a gold standard a realistic possibility.

b. To make a gold standard work, the values of currencies in terms of gold have to keep changing

c. Platinum is now more valuable than gold

d. Monetary authorities generally want to control the supply of money in their countries rather than dependent whatever amount of gold they happen to have at the time.

e. both b and c