Samuel Clemens, _____ Mark Twain, because a famous American writer.

A．was known as

B．known as

C．was known for

D．known for

我国南方某放牧牛群食欲减退，体温升高，精神不振，腹泻便血，严重贫血，衰竭死亡。剖检见肝脾肿大，肝组织内有大量虫卵结节。确诊该病常用的粪检方法是（）

A.饱和盐水漂浮法

B.毛蚴孵化法

C.直接涂片法

D.幼虫分离法

E.离心沉淀法