Assume that all interest rates in the economy decline from 10 percent to 9 percent. Which of the following bonds will have the smallest percentage increase in price? Select one: a. A 3-year bond with a 20% coupon. b. A 20-year zero coupon bond. c. A 10-year bond with a 15% coupon. d. A 5-year bond with a 15% coupon. e. A 10-year zero coupon bond