Two identical charged spheres suspended from a common point by two massless strings of length l, are initially at a distance $d\; (d << l)$ apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then v varies as a function of the distance x between the spheres, as :

Question

( A ) v $\propto$ x
( B ) v $\propto$ x$^{-1}$
( C ) v $\propto$ x$^{\frac{1}{2}}$
( D ) v $\propto$ x$^{-\frac{1}{2}}$