Rank the modified durations of the following pair of bonds and explain your answers: a) Bond A is a 6% coupon bond, with a 20-vear time to maturity selling at par. Bond B is a 6% coupon bond, with a 20-year maturity selling below par. b) Bond A is a 20-year non-callable bond with a coupon rate of 6%, selling at par. Bond B is a 20-year callable bond with a coupon rate of 7%, also selling at par