Which of the following is a density-independent factor?

• A. Weather
• B. Competition
• C. Predation
• D. Disease

Answer: (A)

Density-independent factors affect a population regardless of how many individuals are present, and they are usually abiotic. Weather fits this pattern because events like a severe storm, drought, or extreme cold impact all members of the population in the same way, no matter whether the population is small or large. The effect comes from the external environment, not from how crowded the living space is.

In contrast, the other factors tend to depend on population density. Competition for limited resources becomes more intense as more individuals are present, making outcomes more severe with higher density. Predation and disease often have greater impact when there are more prey or hosts nearby, facilitating more encounters and transmission. So weather stands out as the density-independent factor.