Four equal charges Q are placed at the four comers of a square of each side is 'a'. Work done in removing a charge -Q from its centre to infinity is

• A

  0

• B

  $\frac{\sqrt{2}{\mathrm{Q}}^2}{4{\mathrm{\pi \epsilon }}_0\mathrm{a}}$

• C

  $\frac{\sqrt{2}{\mathrm{Q}}^2}{{\mathrm{\pi \epsilon }}_0\mathrm{a}}$

• D

  $\frac{{\mathrm{Q}}^2}{2{\mathrm{\pi \epsilon }}_0\mathrm{a}}$