A long rectangular copper bar under a tensile load of 180 kN hangs from pin that is supported by two steel posts. The copper bar has a length of 2 m, Ac = 4800 mm, Ec= 120 GPa. Each steel post height of 1m, A = 4500 mm, E, = E = 2x105 MPa. The downward displacement '8' of the lower end of the copper bar due to load is (a) 0.625 mm (c) 0.725 mm (b) 1.625 mm (d) 1 mm