A corporate bond is currently trading at a price that is below its par value. Which of the following statements is the BEST explanation of why this is happening? A. The yield to maturity (YTM) is equal to investors' average required return on this bond. B. This bond has become relatively less risky. C. The bond's coupon rate is higher than its yield to maturity (YTM). D. Interest rates must have increased since the bond was issued