Answer:
D. A large number of Americans became workers in factory in cities.
Step-by-step explanation:
After the advent of industrial revolution, the demand for labors rose tremendously. It was because of these newly generated opportunities to work in the factories in cities, most Americans left their towns to leave for cities.
The life in the cities offered a better standard of living and was facilitated with the availability of amenities and facilities that were not available in smaller towns and villages.