问题如下：
Avelyn comments on the following considerations in a bottom-up approach.
Comment 1 Callable debt has a smaller option-adjusted spread than comparable non-callable debt.
Comment 2 Benchmark corporate bond issues normally have wider spreads than older bonds of the same issuer.
Comment 3 The announcement of a new corporate bond issue often leads to an increase in the credit spread on the existing bonds.
Which of Avelyn’s comments regarding considerations in the bottom-up approach is most accurate?
选项：
A.Comment 1
Comment 2
Comment 3
解释：
C is correct.
When an issuer announces a new corporate bond issue, the issuer’s existing bonds often decline in value and their spreads widen. This dynamic is often explained by market participants as an effect of increased supply. A related reason is that because demand is not perfectly elastic, new issues are often given a price concession to entice borrowers to buy the new bonds. This price concession may result in all of an issuer’s existing bonds repricing based on the new issue’s relatively wider spread. A third reason is that more debt issuance may signal an increase in an issuer’s credit risk.
不明白为什么答案解释里说“commont 1的callable与comparable non-callble两只债券的信用风险是一致”的？
