NO.PZ2020021002000202
问题如下：
The selection of the appropriate systematic factors depends (in part) on judgment and there is no single perfect set of factors for all investors. Why?
选项：
A.
A key challenge is determining how often a hedge needs to be adjusted.
B.Another challenge is model risk
C.all above解释：
C is correct.老师能不能解释一下，虽然做对了但是不理解
