A uniform chain of length L hangs partly from a table which is kept in equilibrium by friction. The maximum length that can withstand without slipping is l, then coefficient of friction between the table and the chain is

(1) $\frac{l}{L}$

(2) $\frac{l}{L+l}$

(3) $\frac{l}{L-l}$

(4) $\frac{L}{L+l}$