What was one effect that mass transit had on American cities?

AMost urban workers no longer had to live in tenements.
BThe number of skyscrapers increased dramatically because there was no room left on the ground.
CConflicts over ethnic and racial divisions declined because people could live farther apart.
DCities marked off separate zones for heavy industry, financial institutions, residences, and public spaces.

Verified Answer :

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.

Answer: “cities marked off separate zones for heavy industry, financial institutions, residences, and public spaces”

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