Solve this:

4.  A system consists of n identical particles of mass m placed rigidly on the vertices of a regular polygon with each side of length a. If K₁ be the kinetic energy imparted to one of the particles so that it just escapes the gravitational pull of the system and thereafter kinetic energy K₂ is given to the adjacent particle to escape, then the difference $\left(K_1 - K_2\right)$ is

$$\begin{gathered} \left(A\right) \frac{nG{m}^2}{a} \left(B\right) \frac{G{m}^2}{na} \\ \left(C\right) \left(\frac{n}{n + 1}\right)\frac{G{m}^2}{a} \left(D\right) \frac{G{m}^2}{a} \end{gathered}$$