The growth of railroads during the late 1800s create a boom for the steel industry becuase Steel rails were much more durable than the iron rails that had been in use.
Option B
Step-by-step explanation:
In the beginning of the year 1800 the railroad construction in the US increase at a exponential rate. And, in around 1860s the "congress" passed "pacific railroad act". This act authorizes construction of transcontinental railroad. This gives a boost to the railway construction and by 1900 four additional transcontinental railroads are made which connects the eastern states with the Pacific Coast. This turns out to be a boon for the steel industry. As, the railroads were the biggest customer of the steel industry. The steel industry used "cheap and efficient methods" for the mass production of steel rails in order to meet the requirements of the railroads.