It is customary to express changes in the exchange rates of two currencies over time, as:

a. the loss of purchasing power of one currency divided by the loss of purchasing power of the other currency.
b. the percentage change expressed as an appreciation or depreciation of one against the other.
c. a ratio of the absolute values (without signs).
d. a ratio of the price of gold in each nation.

Ans: b. the percentage change expressed as an appreciation or depreciation of one against the other.