However, as cities became larger and population densities increased, one major advancement was the development of , which helped to channel wastewaters away from human populations more effectively than in the past. a.Water towers b.Fountains c.Sewer dams d.Dams

Option: c. Sewer

Explanation:

Sewer plays a key role in collecting wastewater from human populations more effectively than in the past. Before, the emergence of cities, there was no proper procedure to collect the wastewater in America, which ultimately affected the environment and underground water. As cities began to take shape in America with a larger population, the sewage system came in the late 1850s in Chicago and Brooklyn.