A `2kg` block slides on a horizontal floor with the a speed of `4m//s` it strikes a uncompressed spring , and compresses it till the block is motionless . The kinetic friction force is compresses is `15 N` and spring constant is `10000 N//m` . The spring by
A. 5.5 cm
B. 2.5 cm
C. 11.0 cm
D. 8.5 cm