Secondary source excerpt (regional analysis): Functional regions are often identified using thresholds, such as "counties where at least 15% of workers commute to the core city." Such thresholds make the concept measurable, but they also reveal that boundaries are partly a methodological choice: a 10% cutoff yields a larger region than a 20% cutoff. This illustrates that nodal regions are constructed from data and criteria rather than discovered as fixed entities. The underlying idea remains the same: a central node organizes surrounding areas through repeated interactions.
Which option best shows how an analyst's threshold affects a functional region's boundary?
- Raising the commuting cutoff from 10% to 20% would likely shrink the mapped commuter-shed around the core city (correct answer)
- Changing the cutoff would have no effect because functional regions exist naturally and are not influenced by methods
- Changing the cutoff would convert the functional region into a uniform region defined by precipitation
- Any cutoff produces a perfectly sharp boundary where commuting becomes zero outside the line
- Raising the cutoff would expand the region because higher thresholds always include more places
Explanation: The passage explains that functional regions are identified using thresholds (like percentage of workers commuting) and that different thresholds yield different sized regions - a 10% cutoff creates a larger region than a 20% cutoff. Option A correctly demonstrates this by stating that raising the commuting cutoff from 10% to 20% would shrink the mapped commuter-shed, as fewer places would meet the higher threshold. Option B incorrectly claims regions exist naturally independent of methods. Option C confuses functional with uniform regions. Option D wrongly suggests perfect sharp boundaries. Option E reverses the logic - higher thresholds are more restrictive and include fewer places, not more. This example illustrates how functional regions are "constructed from data and criteria rather than discovered as fixed entities."