Answer:
D
Explanation:
The other answers discuss other effects of transportation, mainly in people's life. But D is the one that explicitly refers to the industrial revolution. Railroads streamlined the process of textile production and stimulated the growth of the industry and cotton production, allowing producers to save time.
The growth of the textile industry also meant that much more cotton was needed and faster than before. The machines to spin it also improved, but slavery became even more brutal than before because cotton was increasingly profitable.
