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

A

25 mm $$\times$$ 25 mm

B

40 mm $$\times$$ 40 mm

C

50 mm $$\times$$ 50 mm

D

60 mm $$\times$$ 60 mm