Which of the following bonds will be most sensitive to a change in interest rates if all bonds have the same initial yield to maturity? A. a 30-year zero-coupon bond with a $1,000 face value B. a 15-year bond with a $1,000 face value, 5% coupon rate, and semi-annual coupons C. a 20-year bond with a $1,000 face value, 5% coupon rate, and semi-annual coupons D. a 25-year bond with a $1,000 face value, 5% coupon rate, and semi-annual coupons