A new client owns a U$.$S$.$ Treasury bond maturing in $26$ years. She purchased the bond because she was told that Treasury bonds are default risk$-$free. Which one of the following statements about Treasury security risks should you communicate to your client?

A$)$

Treasury bonds do not have interest rate risk because their coupons are fixed at the date of issue.

B$)$

Treasury bonds do not have default risk, but they do have country risk.

C$)$

Treasury bonds do not have default risk, but they do have purchasing power risk.

D$)$

Treasury bonds are risk$-$free because they are backed by the U$.$S$.$ government.