单项选择题

下列电池中,充放电反应不可逆的是(    )
   A.Zn(s)|CuSO4(a)|Cu(s)
   B.Pb(s)|H2SO4(aq)|PbO2(s)
   C.Zn(s)|Zn2+(a1)‖I-(a2)|I2(Pt)
   D.Zn(s)|Zn2+(a1)‖H+(a2)|H2(p)|Pt

A.Zn(s)|CuSO4(a)|Cu(s)

B.Pb(s)|H2SO4(aq)|PbO2(s)

C.Zn(s)|Zn2+(a1)‖I-(a2)|I2(Pt)

D.Zn(s)|Zn2+(a1)‖H+(a2)|H2(p)