Railway track is made of steel segments separated by small gaps to allow for linear expansion. The segment of track is 10 m long when laid at temperature \(17^{\circ} \mathrm{C}\). The maximum temperature that can be reached is \(45^{\circ} \mathrm{C}\). Increase in length of the segment of railway track is ' \(x\) ' \(\times 10^{-5} \mathrm{~m}\). The value of ' \(x\) ' is \(\left(\alpha_{\text{steel }}=\right.\) \(\left.1.2 \times 10^{-5} /{ }^{\circ} \mathrm{C}\right)\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.