The correct answer to this open question is the following.
First, we talk about Burgess's Concentric Zoning theory. It was developed by architect Ernest Burgess in 1925. He established concentric rings, where downtown was the center of the first circle and the other external rings were an inner-city area, a transition zone, a zone for workers and at the end, a residential zone more exclusive.
The other theory is Hoyt's Sector. It stems from the work "The Structure and Growth of Residential Neighborhoods in American Cities," written by Homer Hoyt in 1939, that complemented the Burgess approach. He conceived a central business area, a transitional manufacturing district, a low-class residential area, a middle-class area, and a high-class exclusive area.