The elongation (mm) in a steel bar having a square cross section of dimension 40 mm $$\times$$ 40 mm is 2.5 mm and is subjected to an axial compressive load of P (kN). If the length of the bar is 4 m and modulus of elasticity is E=250 GPa. What is the value of P (kN)?

A

100

B

150

C

200

D

250