Question

the expansion of the rail networks led to
a growth in the steel industry.
a growth in the textile industry.
a decline in the coal industry.
a decline in the meatpacking industry.

Explanation:

Rail networks require steel for construction (rails, locomotives, etc.). So expanding rail networks would increase demand for steel, leading to growth in the steel industry. Textile, coal decline (coal was actually used more for rail, so decline is wrong), and meatpacking decline don't relate to rail expansion logic.

Answer:

A. a growth in the steel industry.