问题如下：
Company XYZ issues two identical bonds at the same time. Bond A is rated AAA grade while Bond B is B+ grade. The most likely risk premium between the two bonds is:
选项：
A. maturity risk premium
B. inflation rate
C. default risk premium
解释：
C is correct.
AAA grade and B+ grade is the credit rating of the bonds. A bond with triple A grade is high quality bond, and a bond with B+ grade is high yield bond (or junk bond). Bond A and Bond B are similar except for the credit rating. Therefore, the most likely risk premium in this question is default risk premium.
这道题说发行两个债券日期相同，没有说到期日也相同吧？