The correct answer is D) the internal combustion engine.
The technology that was able to spread because of the growth of American railroad networks was the internal combustion engine.
This is a heat engine that generates the combustion process in a chamber. The internal combustion engine makes cars, vehicles, and buses work. They use gasoline or diesel to make the combustion. The engine was created by Etienne Lenoir in 1859 and was perfectionated by Nikolaus Otto in 1876. The growth of American railroad networks helped to spread the internal combustion engine.