
Given, that $C_1=C_2=C$ and $C_3=C_4=3 C$.
Which of the following statement($s$) is(are) correct?



$(A)$ the charge on the upper plate of $C _1$ is $2 CV _0$
$(B)$ the charge on the upper plate of $C _1$ is $CV _0$
$(C)$ the charge on the upper plate of $C _2$ is $0$
$(D)$ the charge on the upper plate of $C _2$ is $- CV _0$