Three charges $Q,+q$, and $+q$ are placed at the vertices of a right angle triangle (isosceles triangle) as shown. The net electrostatic energy of the configuration is zero, if $Q$ is equal to
(A) $\frac{-q}{1+\sqrt{2}}$
(B) $\frac{-2 q}{2+\sqrt{2}}$
(C) $-2 q$
(D) $+q$