If the potential can be made zero, then the only possibility is that the total charge
on them are equal In such a case, if opposite polarities are connected,
the potential across the two vanishes.
$ \Rightarrow 120C_1 = 200C_2 \Rightarrow 3C_1 = 5C_2.$
This is a set of three similar question demonstrating a general technique to solve
any circuit with any level of complexity to obtain equivalent resistance.
Ans : (A)