Question

How did Carnegie’s early job with the railroads greatly contribute to his success in the steel business?
It helped him predict that the demand for steel to build railroad tracks and bridges was growing.
It taught him how to lay railroad tracks with steel.
The Pennsylvania Railroad Company was his best customer when he built his business.
The Pennsylvania Railroad Company paid him well enough to eventually invest in his own business.

Answer 1

It helped him predict that the demand for steel to build railroad tracks and bridges was growing.

His railroad work gave him industry knowledge and contacts and made clear the huge, increasing market for steel rails and bridges — a key insight for entering steel.