System shown in figure is released from rest. Pulley and spring is massless and friction is absent everywhere. The speed of 5kg block when 2 kg block leaves the contact with the ground is $(k=40 N/m;g=10 m/s^2)$

Question

$$(a)\;\sqrt 2\;m/s \quad (b)\;2 \sqrt 2\;m/s \quad (c)\; 2\; m/s \quad (d)\;4 \sqrt 2\;m/s$$