Steel bar of $$40 mm \times 40 mm$$ square section is subjected to an axial compressive load of 200 kN. If the length of the bar is 2 m and E (Youngs modulus) = 200 GPa. The elongation of bar will be

A

5.4 mm

B

1.25 mm

C

2.7 mm

D

3.4 mm