问题如下：
Consider a bank that wants to have an amount of capital so that it can absorb unexpected losses corresponding to a firmwide VAR at the 1 % level. It measures firmwide VAR by adding up the VARs for market risk, operational risk, and credit risk. There is a risk that the bank has too little capital because
选项： It does not take into account the
correlations among risks.
It ignores risks that are not market, operational, or credit risks.
C.It mistakenly uses VAR to measure operational risk because operational risks that matter are rare events.
D.It is meaningless to add VARs.
解释：
B is correct. VAR can be added across different types of risk, but this will provide a conservative estimate of capital as diversification effects are ignored. So answer a. would be for too much capital. Answer c. is not correct because rare events can be factored into operational VAR. Most likely, the bank may have too little capital for other types of risk than those measured by these three categories.
我的理解：
题目大意：
公司想有大量的足够覆盖UL的capital（99%VAR）,然后算了market和credit这类主流量化计量的风险，并简单相加得到公司的VAR，但是还是发现自己的capital太少了，原因是什么？
那我觉得a答案是符合逻辑的啊，因为它只是把各个类型的var加总起来，忽律相互之间的分散性，导致了firm var远大于实际，显得自己的capital很小。
请问下我的理解是哪里出了问题？
