Final answer:
The major difference is that density-dependent factors affect populations based on density, while density-independent factors impact populations regardless of density. So the correct option is B.
Step-by-step explanation:
The major difference between density-dependent and density-independent factors is how they affect populations in relation to the population's density. Density-dependent factors influence the population based on its density, meaning their impact becomes more significant as the population density increases. Common examples include predation, competition for resources, and disease, all of which tend to increase mortality or reduce birth rates in denser populations. In contrast, density-independent factors will affect the population regardless of its density. These factors are usually abiotic, such as weather extremes, natural disasters, or human activities like pesticide use, and can cause mortality in a population no matter whether it is large or small.