问题如下：
When determining the standard deviation of value due to credit quality changes for a single exposure, the CreditMetrics model uses three primary factors. Which of the following is not one of the factors used in this model?
选项： Credit
ratings
Seniority
C.Equity prices
D.Credit spreads
解释：
ANSWER: C
CreditMetrics uses credit ratings, the transition matrix, recovery rates, and LGD for various seniorities, but not equity prices for the obligor.
请问，为什么不选C？讲义341页，提到大部分模型都没考虑credit spread
另外，seniority是怎么体现出来的
