Suppose the U.S. Treasury offers to sell you a bond for $660. No payments will be made until the bond matures 10 years from now, at which time it will be redeemed for $1,000. What interest rate would you earn if you bought this bond at the offer price?

a. 4.24%

b. 3.85%

c. 6.40%

d. 4.73%

e. 15.15%