What was one effect that mass transit had on American cities?
a. Most urban workers no longer had to live in tenements.
b. The number of skyscrapers increased dramatically because there was no room left on the ground.
c. Conflicts over ethnic and racial divisions declined because people could live farther apart.
d. Cities marked off separate zones for heavy industry, financial institutions, residences, and public spaces.
The best answer is B. The number of skyscrapers increased a lot because there was no room left on the ground. Instead of expanding vertically, companies are left with no choice but to expand infrastructures horizontally because of the mass transit system in the cities.
