Final answer:
Extinction is less likely in stochastic models that include density dependence because these factors increase a population's resilience and recovery chances after declines. Density-dependent regulation, such as predation and competition, stabilizes populations by scaling effects with population size. Option a is the correct answer.
Step-by-step explanation:
Extinction is less likely in models of stochastic extinction that include density dependence because such models consider the role of population density in the growth and survival of species. Density-dependent factors can lead to increased resilience in populations because as population density decreases, due to any stochastic events, such as natural disasters, the per capita death rate may decrease and the per capita birth rate may increase leading to greater chance of population recovery.
In contrast, density-independent factors occur regardless of population density and can have a significant negative impact on populations, without any buffering effect that can come from density dependence. This includes events like a harsh winter or a pesticide application that affects all members of a population equally, regardless of its size.
Density-dependent regulation, which includes mechanisms like predation, competition, and disease, tends to stabilize the population because the effects scale with population size. A low-density population may have higher survival rates and reproductive success due to reduced competition and predation pressure, enhancing recovery after a decline and reducing the risk of extinction.