Which of the following bonds have the highest default risk for a given return?

Select one:

a. A U.S Treasury bond with a 2-year maturity.

b. An AAA corporate bond with a 7-year maturity.

c. A BBB corporate bond with a 3-year maturity.

d. A CCC corporate bond with a 10-year maturity.

e. An AAA corporate bond with a 3-year maturity.