The Horizontal Surface on Which the Block Slides Is Frictionless

The horizontal surface on which the block slides is frictionless. The speed of the block before it touches the spring is 6.0 m/s. How fast is the block moving at the instant the spring has been compressed 15 cm? k = 2.0 kN/m

A) 3.7 m/s
B) 4.4 m/s
C) 4.9 m/s
D) 5.4 m/s
E) 14 m/s