______ we all know is ______ the old gentleman, for ______ life was hard in the past, still works every day. [ ]

A. What; /; whom

B. What; that ;whose

C. It; / ; whom

D. What; that; whom

关于肛门内括约肌的论述，下列哪一项是错误的：

A．起着括约肛门的作用

B．受自主神经支配

C．是直肠环状肌在肛管上部的肥大部分

D．长度约3cm

E．很容易暴露于手术切口处