Which of the following is an example of the law of one price?

a. Exchange rates tend to have equivalent values. For example, one euro equals one U.S. dollar.
b. Because people have essentially the same basic needs wherever they live, they tend to buy the same bundle of goods.
c. Because wages are so much lower in China, eventually all U.S. jobs will be outsourced to China, leaving the United States to import all goods at one price.
d. Because their countries have similar institutions, computer programmers in Germany and the United States either are or will be paid about the same.