问题如下图：
选项：
A. 
B. 
C. 
D. 
解释：
能具体解释一下C、D吗？
1.C中EDF与Merton model的risk neutral PD到底有什么区别？前者时由历史数据获得，后者是由二叉树获得？
2.D上课时候KMV好像没有讲到ρ的关系把？
The KMV mol proces a measure calleexpectefault frequency. Whiof the following statements about this variable is correct? It creases when the leverage of the firm falls. It increases when the stopriof the firm hbeen rising. It is the risk-neutrprobability of fault from Merton’s mol. It tells investors how the fault risk of a bonis correlatewith the fault risk of other bon in the portfolio ANSWER: A The E, similarly to the risk-neutrP creases when the stoprigoes up, when the leverage goes wn, or when the volatility goes wn. It is a transformation of the Pfrom a Merton-type mol. The KMV framework cextento finng correlations, but the E is not sufficient. 为什么当stoprigoes up，or leverage goes wn时，会下降？
It increases when the stopriof the firm hbeen rising. It is the risk-neutrprobability of fault from Merton’s mol. It tells investors how the fault risk of a bonis correlatewith the fault risk of other bon in the portfolio ANSWER: A The E, similarly to the risk-neutrP creases when the stoprigoes up, when the leverage goes wn, or when the volatility goes wn. It is a transformation of the Pfrom a Merton-type mol. The KMV framework cextento finng correlations, but the E is not sufficient. 请问一下C和应讲义的哪里？
It increases when the stopriof the firm hbeen rising. It is the risk-neutrprobability of fault from Merton’s mol. It tells investors how the fault risk of a bonis correlatewith the fault risk of other bon in the portfolio ANSWER: A The E, similarly to the risk-neutrP creases when the stoprigoes up, when the leverage goes wn, or when the volatility goes wn. It is a transformation of the Pfrom a Merton-type mol. The KMV framework cextento finng correlations, but the E is not sufficient. E在讲义的哪一部分？
没看懂这道题考点
