Using the external work done and internal work stored within this rod ABC, what is the total axial deformation of the rod if the applied force $P$ is $25$ kN $?$

Assume $E=200$GPa.

A$.0\mathrm{.}138$ mm

B$.0\mathrm{.}476$ mm

C$.0\mathrm{.}837$ mm

D$.0\mathrm{.}975$ mm