Answer:v
Step-by-step explanation:
Given
Initially spring mass system is moving towards right with velocity

Now if the spring is released left block moves towards left with a velocity

As there is no external force applied on the system therefore the change in linear momentum is zero i.e. it is conserved
so center of mass continue to move towards the right with velocity v or we can say right block moves towards right with velocity
and left block moves with velocity
