$n_1$ identical capacitors, each of capacitance $C_1$ are connected in series and charged by a source of potential difference 3 V. $n_2$ identical capacitors, each of capacitance $C_2$ are connected in parallel and charged by a source of potential difference 2 V. Total energy stored in both the combinations is the same. What is the value of capacitance $C_2$ in terms of $C_1$?

$\frac{9 C_1}{4 n_1 n_2}$

The correct answer is Option (2) → $\frac{9 C_1}{4 n_1 n_2}$