问题如下：
The process of moving credit ratings of different issues up or down from the issuer rating in response to different payment priorities is best described as:
选项：
A.notching.
B.structural subordination.
C.cross-default provisions.
解释：
A is correct.
Notching is the process for moving ratings up or down relative to the issuer rating when rating agencies consider secondary factors, such as priority of claims in the event of a default and the potential loss severity.
请问C能解释一下吗？谢谢！
