A newly issued non-callable fixed-rate bond with 30 year maturity carries a
coupon rate of 5.5% and trades at par. Its duration is 15.33 years and its
convexity is 321.03. Which of the following statements about this bond is true?
A. If the bond were to start trading at a discount, its duration would decrease
B. If the bond were to start trading at a premium, its duration would decrease.
C. If the bond were to start trading at a discount, its duration would not change.
D. If the bond were to remain at par, its duration would increase as the bond aged.
答案是A，不懂他的意思，及如何判断
感谢指教