A chain is held on a frictionless talbe with `L//4` hanging over. Knowing total mass of the chain is `M` and total length is `L`, the work required to slowly pull hanging part back to the table is `:`
A. `(MgL)/(16)`
B. `(MgL)/(8)`
C. `(MgL)/(32)`
D. `(MgL)/(24)`