A block of mass m is connected to a spring and passed over a pulley as shown in figure. The block is released from rest with the spring outstretched. Force constant of spring is k. Find the maximum extension in the spring .

Question

$\begin{array}{1 1} \large\frac{mg}{k} \\ \large\frac{mg}{2k} \\ \large\frac{2mg}{k} \\ 0 \end{array} $