Suppose you have just received $10,000 from a relative. You are trying to decide whether to put the $10,000 in a non-interest-bearing checking account so that you can use it whenever you want or to use it to buy a U.S. Treasury bond. If the interest rate on the bond is 7 percent per year, the opportunity cost of holding the $10,000 as money is
a. $700 per year
b. $654 per year
c. $10,000 per year
d. $7 per year