Bond C and Bond D both have a face value of $1000, and each carries a 4.2% coupon. Bond C matures in 3 years and Bond B matures in 23 years. If the prevailing required rate of return in the bond market suddenly rises from the current 4.5% to 4.8% compounded semiannually, how much will the market price of each bond change? What general rule does this outcome demonstrate?