Mother often _____ elder brother _____ little brother.        [ ]

A. mistake; for

B. mistook; as

C. mistakes; for

D. mistake; as

高级计量法在计量操作风险时认可保险的风险缓释影响，但保险的缓释作用不超过操作风险总资本要求的（）。

A．10%

B．15%

C．18%

D．20%