Three chargers Q, + q and + q are placed at the vertices of a right angle triangle ( isoceles triangle ) as shown . If the net electrostatic potential energy of the configuration is zero, value of Q is

Question

$\begin {array} {1 1} (1)\;\large\frac{+q}{2+\sqrt 2} & \quad (2)\;\large\frac{-q}{2+\sqrt 2} \\ (3)\;\large\frac{+2q}{2+\sqrt 2} & \quad (4)\;\large\frac{-2q}{2+\sqrt 2} \end {array}$