A Steel Spring Having Spring Constant $k _ { s }$

A steel spring having spring constant $k _ { s }$ and length $L _ { s }$ is placed in series with a brass spring having spring constant $k _ { b }$ and length $L _ {b }$ . The two springs are then inserted into a vise (in a coaxial arrangement) , and the vise squeezes the springs a distance $d$ . The entire length of the compressed steel spring is

A) $L _ { s } - k _ { b } d / \left( k _ { b } + k _ { s } \right)$
B) $L _ { s } - k _ { b } L _ { b } / \left( k _ { b } + k _ { s } \right)$
C) $L _ { b } - k _ { s } L _ { s } / \left( k _ { b } + k _ { s } \right)$
D) $L _ { s } - k _ { s } d / \left( k _ { b } + k _ { s } \right)$