Which change occured as a result of urbanization. a. the invention of the assembly. b. the crowding of people in tenements and slums. c. the dropping of prices due to the use of the assembly line. d. the creation of "big business"

 B. The crowding of people in tenements and slums.

Further detail:

The Industrial Revolution had its beginning in Great Britain, and eventually spread from there.  Once the United States became involved, especially in the "Second Industrial Revolution" years (1870-1914), the size and resources of the country allowed the US to become a bigger industrial power than the nations of Europe.

Industrialization also led to the phenomenon of urbanization -- the movement of people away from the rural countryside and into cities.   That led to other issues, like sanitation and crime problems in cities.  So sanitation and health measures were enacted, and the first police forces were formed.

The overcrowding conditions also meant poor living conditions in tenements and slums.  The condition of these sorts of neighborhoods was documented by Jacob Riis, a police reporter in New York.  In 1888, Riis took pictures of what life was like in New York City's slums.  Using his own photos as well as photos gathered from other photographers, Riis began to give lectures titled, "The Other Half: How It Lives and Dies in New York," in which he would show the pictures on a projection screen and describe for viewers what the situations were like.  He gave his lectures in New York City churches.  In 1989, a magazine article by Riis (based on his lectures) was published in Scribner's Magazine.  The book version was then published in 1890 as How the Other Half Lives: Studies among the Tenements of New York.  Riis blamed the poor living conditions on greed and neglect from society's wealthier classes, and called on society to remedy the situation as a moral obligation.

that is probably something for you to answer