A steel rod of sectional area 25 sq. mm connects two parallel walls 5 m apart. The nuts at the ends were tightened when the rod was heated at $$100^\circ$$ C. If $$\alpha$$ steel = 0.000012/$$C^\circ$$, Esteel = 0.2$$MN/mm^{2}$$, the tensile force developed at a temperature of $$50^\circ$$ C is _____

A

80 $$\frac{N}{mm^{2}}$$

B

100 $$\frac{N}{mm^{2}}$$

C

120 $$\frac{N}{mm^{2}}$$

D

150 $$\frac{N}{mm^{2}}$$