Which of the following is an example of external obsolescence?

External obsolescence refers to a reduction in property value caused by external factors, typically related to the location or neighborhood surrounding the property, rather than issues inherent to the property itself. A decrease in neighborhood popularity is a prime example of this concept, as it reflects changing perceptions or conditions in the external environment that can negatively impact property values. Factors such as increased crime rates, declining local amenities, or economic downturns in the area can lead to fewer buyers wanting to purchase in that neighborhood, ultimately affecting the property values adversely.

In contrast, the other options focus on issues that stem from the property itself: wear and tear on a roof relates to physical deterioration, outdated kitchen fixtures pertain to the internal condition and updates of the property, and a cracked foundation indicates structural problems. These are all types of physical depreciation or functional obsolescence, which are distinguished from external obsolescence that is external to the specific property itself. Understanding these distinctions is crucial in real property appraisal, as it helps in accurately assessing the value of a property in the context of its environment.