The end of a cylindrical rod 6.4 mm in diameter and 250 mm long are mounted between rigid supports. The rod is stress-free at room temperature (20C); upon cooling to -40C, a maximum thermally induced tensile stress of 125 MPa (18,125 psi) is possible. Of which of the following metal or alloys may the rod be fabricated?

a. Brass

b. Tungsten

c. 1025 steel

d. Aluminum

e. Copper

Please show every step.