Early models of the geography of the metropolis were

Early models of the geography of the metropolis were unicellular: that is, they assumed that the entire urban district would normally be dominated by a single central district, around which the various economic functions of the community would be focused. This central business district (CBD) is the source of so-called high-order goods and services, which can most efficiently be provided from a central location rather than from numerous widely dispersed locations. Thus, retailers of infrequently and irregularly purchased goods, such as fur coats, jewelry, and antique furniture, and specialized service outlets, such as theaters, advertising agencies, law firms, and government agencies, will generally be found in the CBD. By contrast, less costly, more frequently demanded goods, such as groceries and housewares, and low-order services, such as shoe repair and hairdressing, will be available at many small, widely scattered outlets throughout the metropolis.
Both the concentric-ring model of the metropolis, first developed in Chicago in the late nineteenth century, and the sector model, closely associated with the work of Homer Hoyt in the 1930s, make the CBD the focal point of the metropolis. The concentric-ring model assumes that the varying degrees of need for accessibility to the CBD of various kinds of economic entities will be the main determinant of their location. Thus, wholesale and manufacturing firms, which need easy accessibility to the specialized legal, financial, and governmental services provided in the CBD, will normally be located just outside the CBD itself. Residential areas will occupy the outer rings of the model, with low-income groups residing in the relatively crowded older housing close to the business zone and high-income groups occupying the outermost ring, in the more spacious, newer residential areas built up through urban expansion.
Homer Hoyt’s sector model is a modified version of the concentric-ring model. Recognizing the influence of early established patterns of geographic distribution on the later growth of the city, Hoyt developed the concept of directional inertia. According to Hoyt, custom and social pressures tend to perpetuate locational patterns within the city. Thus, if a particular part of the city (say, the east side) becomes a common residential area for higher-income families, perhaps because of a particular topographical advantage such as a lake or other desirable feature, future expansion of the high-income segment of the population is likely to proceed in the same direction. In our example, as the metropolis expands, a wedge-shaped sector would develop on the east side of the city in which the higher-income residence would be clustered. Lower-income residences, along with manufacturing facilities, would be confined, therefore, to the western margins of the CBD.
Although Hoyt’s model undoubtedly represented an advance in sophistication over the simpler concentric-ring model, neither model fully accounts for the increasing importance of focal points other than the traditional CBD. Recent years have witnessed he establishment around older cities of secondary nuclei centered on suburban business districts. In other cases, particular kinds of goods, services, and manufacturing facilities have clustered in specialized centers away from the CBD, encouraging the development of particular housing patterns in the adjacent areas. A new multicellular model of metropolitan geography is needed to express these and other emerging trends of urban growth.

7. All of the following are examples of the emerging trends of urban growth described in the last paragraph of the passage EXCEPT
(A) the construction in a suburban community of a large shopping mall where many of the local residents do most of their buying
(B) the opening of an industrial park on the outskirts of a declining older city
(C) the construction of hospital-medical school complex near a highway fifteen miles from a downtown business district
(D) the building of a residential development near a suburban tool factory to house the factory workers and their families
(E) the creation of a luxury housing development in a rural setting thirty miles from the center of a city