Which of the following is a density-independent factor affecting population?

Density-independent factors are environmental influences that affect a population regardless of its density. These factors can dramatically impact population sizes but do not depend on how densely populated an area is.

Climate extremes, such as droughts or hurricanes, are prime examples of density-independent factors. These events can lead to substantial reductions in population size irrespective of how many individuals are there; for instance, a drought can cause water scarcity that affects all organisms within an area equally, regardless of their current population density.

In contrast, predation by an increased number of predators and competition for resources are density-dependent factors, as their effects are directly related to the population density; for example, as prey populations increase, so too do predator populations, leading to a higher predation rate. Pesticide application, while it can reduce population size, is an anthropogenic action that affects the population without consideration for its density but is often categorized differently than the natural environmental factors like climate extremes. Therefore, climate extremes like drought or hurricanes are the correct choice for a density-independent factor affecting population dynamics.