What will be the stress at $-20^{\circ} \mathrm{C}$, if a steel rod with a cross-sectional area of $150 \mathrm{~mm}^{2}$ is stretched between two fixed points? The tensile load at $20^{\circ} \mathrm{C}$ is $5000 \mathrm{~N}:$ (Assume $\alpha=11.7 \times 10^{-6} /{ }^{\circ} \mathrm{C}$ and $Y=200 \times 10^{11} \mathrm{~N} / \mathrm{m}^{2}$ )
(a) $12.7 \times 10^{6} \mathrm{~N} / \mathrm{m}^{2}$
(b) $1.27 \times 10^{6} \mathrm{~N} / \mathrm{m}^{2}$
(c) $127 \times 10^{6} \mathrm{~N} / \mathrm{m}^{2}$
(d) $0.127 \times 10^{6} \mathrm{~N} / \mathrm{m}^{2}$