Which of the following factors can lead to overcrowding?

1. Analyze the question The question asks which factor leads to overcrowding, meaning too many individuals living in a given area. This is a topic in population ecology.

2. Explain the concept Population size changes according to four factors:

• Natality (birth rate) and immigration increase a population.
• Mortality (death rate) and emigration decrease a population.

Overcrowding happens when a population grows beyond what the habitat's resources can support (its carrying capacity). So we look for the factor that adds individuals to the population.

3. Evaluate each option

• A. Emigration: Individuals leave the area, so the population falls. This reduces overcrowding.
• B. Competition: This is a result of overcrowding, since individuals compete for limited food, water and space. It does not cause overcrowding.
• C. High natality: A high birth rate adds many new individuals quickly, which increases population density and leads to overcrowding.
• D. High mortality: Many individuals die, so the population shrinks. This reduces overcrowding.

4. Answer The correct option is C. High natality.

5. Exam tip Remember: "Births and Immigrants In, Deaths and Emigrants Out." Anything that adds individuals (natality, immigration) can cause overcrowding. Anything that removes them (mortality, emigration) relieves it. Also note that competition is a consequence of overcrowding, not a cause, which is a common trap in JAMB questions.