The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant $k$ and compresses it by length $L$. The maximum momentum of the block after collision is : <br>

Question

( A ) $\frac{kL^2}{2M}$
( B ) zero
( C ) $\frac{ML^2}{k}$
( D ) $\sqrt{Mk} L$