A Block of Mass M Is Pushed Against a Spring

Multiple Choice

A block of mass m is pushed against a spring of spring constant k. The spring is compressed by a distance d, the block is then released. It is launched by the spring along a horizontal frictionless surface with a final speed v. A second block, this one having mass 4m is pushed against the same spring by distance 6d and released. What is the final speed of the block in this case?

A) v
B) 2v
C) 3v
D) 4v
E) 5v