Which factor contributed most to the rise of inner-city overcrowding in the late nineteenth century?

People from all over the world were immigrating abroad in search for better work and social conditions.

Explanation:

The United States was the fastest growing economy in the World, thus many factories and businesses were hiring more and more people. In addition, people living in rural areas inside the US were also moving in to the cities or the suburbs. Soon, however the cities were overcrowding and along with it came problems such as traffic, noise, pollution and a need for better infrastructure and health systems. Immigrants coming from all over the world began to settle in neighborhoods and it gave birth to communities inside the big cities that kept the traditions and customs of their countries of origin. We can find most them even in the modern era.

answer; ///i do believe that the correct answer is (d); ///athens had a small population;

confederacy: supported slavery, believed states should be able to nullify federal laws, supported low tariffs

union: everything else