Point charge $$q$$ is kept at each corner of a cube of edge length $$l$$. The resultant force of repulsion on any one of the charges due to all others is expressed as

A

$$\frac{q^2}{\pi\epsilon_0 l^2}\left(1 + \frac{1}{2\sqrt{2}} + \frac{1}{3\sqrt{3}}\right)$$

B

$$\frac{\sqrt{3}q^2}{\pi\epsilon_0 l^2}\left( \frac{1}{2\sqrt{2}} -1 + \frac{1}{3\sqrt{3}}\right)$$

C

$$\frac{1 - 0.1775 q^2}{\pi \epsilon_0 l^2}$$

D

none of these