This question has TWO parts. Please be sure to scroll down and make sure you answer both parts.

Which of the following bonds will be least sensitive to a change in int$$rest rates if all bonds have the same initial yield to maturity?

A$.$ a $20-$ year bond with a $$1,000$ face value whose coupon rate is $7\mathrm{.}5\%$ APR paid semiannually

B$.$ a $20-$ year bond with a $$1,000$ face value whose coupon rate is $5\mathrm{.}1\%$ APR paid semiannually

C$.$ a $10-$ year bond with a $$1,000$ face value whose coupon rate is $7\mathrm{.}5\%$ APR paid semiannually

D$.$ a $10-$ year bond with a $$1,000$ face value whose coupon rate is $5\mathrm{.}1\%$ APR paid semiannually

A measurement of the sensitivity of a bond's price to changes in interest rates is known as: $($choose the most appropriate answer below$)$

A$.$ Yield to Maturity $($YTM$)$

B$.$ Credit Ri$$s

C$.$ Repayment Risk

D$.$ Duratio