Final answer:
Density-independent factors affect population sizes regardless of the population's density and include weather, natural disasters, and geographical barriers. The correct answer to the question is E. All of the choices.
Step-by-step explanation:
In the environmental factor regulation of population size in natural environments, density-independent factors are those that affect population sizes regardless of the population's density. These include abiotic factors such as weather, natural disasters, and pollution. For example, harsh weather conditions such as a severe winter or a forest fire will impact the survival of individuals in a population whether that population is dense or sparse. Unlike density-dependent factors, which vary with the population's density, density-independent effects are typically the same regardless of how crowded a population is.
Considering the options provided, we can determine that factors such as weather (B), natural disasters (C), and geographical barriers (D) are all considered density-independent factors. Therefore, the correct option for density-independent factors impacting population size would be E. All of the choices.