How to solve 31st sum ?

31. Four metallic plates of equal surfae are A are arranged, as shown. The equivalent capacitance between A and B is.

$$\begin{gathered} \left(\mathrm{A}\right) \frac{{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}} \left(\mathrm{B}\right) \frac{3{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}} \\ \left(\mathrm{C}\right) \frac{3{\mathrm{\epsilon }}_0\mathrm{A}}{2\mathrm{d}} \left(\mathrm{D}\right) \frac{2}{3}\frac{{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}} \end{gathered}$$