Population growth is limited by which broad category of factors?

• A. Limitations imposed by the environment.
• B. Predators alone.
• C. Environmental factors.
• D. Genetic constraints.

Answer: (C)

External conditions in the environment limit population growth by shaping resource availability and the conditions for survival and reproduction. These environmental factors determine how much food, water, shelter, and suitable habitat are available, as well as how climate, disease, and interactions with other organisms affect a population. Together, these influences set the carrying capacity—the maximum population size that the environment can sustain over time—and cause growth to level off when resources become scarce or conditions become harsh. Predation is one piece of the environmental picture, but many other factors like resource supply, disease, and climate also play a role, so the broad category that best captures all these external constraints is environmental factors. Genetic constraints, by contrast, are internal and not about external limits, so they don’t describe the main set of factors that limit growth.