A point charge q is placed in front of a conducting solid cube of edge a at a distance d from its centre (d >a/2). What is the magnitude of electric field at the centre of the cube due to the charges appearing on its surface? $ \displaystyle \left( k=\frac{1}{4\pi {{\epsilon }_{0}}} \right)$

A) $\displaystyle \frac{kq}{{{d}^{2}}}$

B) $\displaystyle \frac{kq}{{{\left( \frac{a}{2} \right)}^{2}}}$

C) 0

D) $\displaystyle \frac{kq}{{{\left( d-\frac{a}{2} \right)}^{2}}}$

E) None of the options given