Which of the following statements about the duration of bonds are true? 1. The duration of a zero-coupon bond is equal to its maturity. II. All else being equal, bonds are more sensitive to changes in interest rates in a low-interest rate environment III. Coupon bonds have higher durations than zero-coupon bonds IV. The coupon rate is inversely related to duration Select one: a. I and 11 b. I and IV c. II and III d. I, II and IV e. All statements are true