Given its time to maturity, the duration of a zero-coupon bond is A. higher when the discount rate is higher B. higher when the discount rate is lower C. lowest when the discount rate is equal to the risk-free rate D. the same regardless of the discount rate All other things equal (YTM = 10%), which of the following has the longest duration? A. a 30-year bond with a 10% coupon B. a 20-year bond with a 9% coupon C. a 20-year bond with a 7% coupon D. a 30-year zero-coupon bond