Answer:
Correct Answer:
The rapid growth of urban America and the influx of millions of immigrants.
Step-by-step explanation:
During the late nineteenth century, there was a great control of the political machines by few individuals. They helped in determining the direction an election would swing to through their political networks and contacts.
These political bosses were able to control such political machinery as a result of the rapid growth of the urban America. Also, the influx of immigrants from China, Europe and other parts of the world helped towards this.