__seems easy to some people seems difficult to others .

A．Which

B．That

C．What

D．Whatever

下列关于乳痈威因的论述，哪项是正确的？（）

A.邪壅经络，郁闭不通

B.气血两虚，邪毒内陷

C.营卫不和，火毒内生

D.肝气郁结，胃热壅滞

E.以上都不是