Final answer:
External obsolescence refers to a decrease in property value due to factors outside the property, such as a nearby railroad track, not related to the property's internal features or designs.
Step-by-step explanation:
External obsolescence pertains to a reduction in a property's value caused by external factors outside the property itself. A typical example of external obsolescence is having a railroad track running alongside the lot. This environmental factor is beyond the control of the homeowner and can detract from the property's desirability and marketability due to noise, vibration, and other nuisances. External obsolescence is unrelated to the home's internal features, such as the size of the kitchen, the location of bedrooms in relation to the bathroom, or whether a family room is located in the basement—all of which constitute functional obsolescence if they do not meet current market preferences.
An external obsolescence refers to a factor outside of a property that affects its value or desirability. In the given options, the most relevant example of external obsolescence is c. a railroad track running alongside the lot. The presence of a railroad track can negatively impact the value of a property due to noise, vibrations, and potential safety concerns. This external factor is beyond the control of the homeowner and can have a significant impact on property value and desirability.