Identical charges (–q) are placed at each corner of a cube of side 'b' then electrical potential energy of charge (+q) which is placed at centre of cube will be

Question

( A ) $\frac{-4\sqrt2q^2}{\pi\epsilon_0 b}$
( B ) $\frac{-8\sqrt2q^2}{\pi\epsilon_0 b}$
( C ) $\frac{-4q^2}{\sqrt\pi\epsilon_0b}$
( D ) $\frac{8\sqrt2q^2}{4\pi\epsilon_0 b}$