Final answer:
Disease (b) is a density-dependent factor affecting the growth rate of a coyote population in Southern Ontario since diseases tend to spread more rapidly and have a greater impact as the density of the population increases.
Step-by-step explanation:
In the context of a population of coyotes in Southern Ontario, a density-dependent factor is one that affects the population growth rate based on the population's size or density. Options (a) through (d) present various factors that could influence the population size of coyotes. Among the listed options, disease (b) is a density-dependent factor because the spread and impact of diseases typically increase as the population density rises, leading to higher mortality rates amongst the coyotes. In contrast, weather conditions (d) are often considered density-independent factors since their effects tend to be uniform across the population, regardless of its size.