A square of side ?a? has charge Q at its centre and charge ?q? at one of the corners. The work required to be done in moving the charge ?q? from the corner to the diagonally opposite corner is [UPSEAT 2004]

• A.            Zero
• B.            \[\frac{Qq}{4\pi {{\in }_{0}}a}\]
• C.                    \[\frac{Qq\sqrt{2}}{4\pi {{\in }_{0}}a}\]
• D.                                      \[\frac{Qq}{2\pi {{\in }_{0}}a}\]