A house located next to an airport would be an example of which type of obsolescence?

The scenario of a house located next to an airport exemplifies economic or external obsolescence because this type of obsolescence arises from external factors that negatively impact the property's value. In this case, the proximity to an airport may introduce noise pollution, limited privacy, and other environmental nuisances, contributing to a decrease in desirability and, consequently, market value. This form of obsolescence is not due to the house itself but rather the external conditions imposed by the surrounding environment.

In contrast, functional obsolescence refers to a property's inherent design flaws or outdated features that lessen its utility. Physical deterioration deals with the physical wear and tear of the structure itself, which occurs over time due to neglect or age. Physical depreciation, while sometimes used interchangeably with deterioration, generally refers more broadly to the decline in value from all causes. Hence, the correct choice highlights how external factors, such as airport operations, can have a profound impact on real estate values, independent of the property itself.