Final answer:
The concentric zone model proposes that the zones of a city are differentiated primarily by their economic function.
Step-by-step explanation:
In the concentric zone model, the zones of a city are differentiated primarily by their economic function.
Zone A, located at the center of the city, is the business and cultural district. Zone B, surrounding the city center, consists of formerly wealthy homes that have been split into cheap apartments for new immigrant populations and also includes small manufacturers and pawn shops.
Zone C is where the working class and established ethnic enclaves reside. Zone D contains wealthy homes, white-collar workers, and shopping centers. Zone E encompasses the upper-class estates in the exurbs and suburbs.