A 0500-Kg Object Rests on a Horizontal Frictionless Surface

A 0.500-kg object rests on a horizontal frictionless surface. It is in a position such that it is compressing a spring a distance 12.0 cm. If the object is released, the object leaves the spring at a speed of 20.0 cm/s. What is the spring constant of the spring?

A) 2.78 N/m
B) 2.19 N/m
C) 3.17 N/m
D) 1.39 N/m
E) 0.333 N/m