Define distance decay and provide an example of its effect on interaction.

• A. Distance decay means interaction increases with distance.
• B. Distance decay means the likelihood of interaction decreases as distance increases.
• C. Distance decay refers to slowing of trade due to time zones.
• D. Distance decay is about data reliability.

Answer: (B)

Distance decay is the idea that interaction between places decreases as distance between them increases. As distance grows, the costs and effort to move people, goods, or information rise, making exchanges less likely. A classic example is trade between cities: nearby cities tend to trade more than distant ones because shipping costs and transit times grow with distance, reducing the volume of goods exchanged. This pattern also shows up in commuting or social interactions, where people are more likely to interact with nearby locations. The concept isn’t about increasing interaction with distance, nor is it about time zones or data reliability.