单项选择题

A.Zn│ZnCl2(aq)│Cl2(g)│Pt
B.Zn│ZnCl2(aq)‖KCl(aq)│AgCl(s)│Ag
C.Ag│AgCl(s)│KCl(aq)│Cl2(g)│Pt
D.Hg│Hg2Cl2(s)│KCl(aq)‖AgNO3(aq)│Ag