What environmental factor prevents a population from increasing?

• A. limiting factor
• B. carbon cycle
• C. organ system
• D. Tides

Answer: (A)

When a population stops growing, it’s because something in the environment is preventing further increase. That "something" is a limiting factor—any resource or condition that reduces the population’s growth rate. Limiting factors include things like not enough food or water, lack of space, too many predators, or the spread of disease. When these limits are reached, the population can level off and stay around a carrying capacity rather than keep rising endlessly.

The other options don’t describe what keeps a population from growing. The carbon cycle explains how carbon moves through air, water, and living things, not the limits on population size. An organ system is a part of an individual organism, not a population-level constraint. Tides are rhythmic changes in sea level driven by gravity and ocean dynamics, which affect coastal organisms but aren’t a general factor that prevents a population from increasing.