A solid brass $E=100$GPa axial member is loaded and supported as shown in Figure. Segments $(1)$ and $(2)$ each have a diameter of $25$ mm and segment $(3)$ has a diameter of $14$ mm $.$ Determine:

$($a$)$ the deformation of segment $(2).$

$($b$)$ the deflection of joint D with respect to the fixed support at A $.$

$($c$)$ the maximum normal stress in the entire axial member.