A chain of mass M is placed on a smooth table with $\large\frac{1}{n}$$^{th}$ of its length L hanging over the edge. The work done in pulling the hanging portion of chain back to the surface of table is

Question

$$(a)\;\frac{MgL}{n}\quad (b)\;\frac{MgL}{2n} \quad (c)\;\frac{MgL}{n^2} \quad (d)\;\frac{MgL}{2n^2}$$