What is used to measure the proportion of a given area used for residential purposes?

The correct choice identifying the measure of the proportion of a given area used for residential purposes is density. Density specifically refers to the number of units (like homes) in a given area, which helps gauge how residentially developed a particular region is compared to its overall size. When urban planners or organizations assess an area, they often look at density to understand how much of that area is designated for housing compared to commercial, industrial, or undeveloped zones.

Demand, while it relates to the need for housing and can influence market trends, does not measure the actual proportion of land used for residential purposes. Depreciation pertains to the loss of value of property over time and is not directly tied to the allocation of land uses. A designated agency might be responsible for overseeing zoning regulations or real estate developments, but it does not quantify land utilization itself. Understanding the concept of density is crucial when evaluating urban development and planning, as it provides insights into housing availability and community structure.