Which of the following is an example of a density-independent limiting factor?

• A. Competition for resources
• B. Predation
• C. Human activity
• D. Disease outbreaks

Answer: (C)

Density-independent limiting factors reduce a population regardless of how many individuals are present; they are usually abiotic or human-caused events that affect survival or reproduction no matter the population size. Human activity fits this because actions like habitat destruction, pollution, or land-use change can lower populations regardless of whether there are many or few individuals.

In contrast, competition for resources depends on how many organisms are trying to use the same limited resources—the more individuals, the greater the competition. Predation effects often scale with prey density because more prey can support more predators or increase encounter rates. Disease outbreaks tend to spread more quickly when population density is high, increasing transmission. Thus, the example that best fits a density-independent factor is human activity.