I haven't read        of the articles carefully, but I find that there is a striking similarity between them.[ ]

A. each

B. either

C. any

D. neither

只用一种试剂，即可一次性鉴别K₂SO₄、NaOH和AgNO₃三种溶液，这种试剂是（　　）

A．BaCl₂

B．FeCl₃

C．NaCl

D．H₂SO₄