Which of the following would NOT cause a population size to decrease?

• A. Increased immigration
• B. Increased emigration
• C. Higher mortality rate
• D. Lower birth rate

Answer: (A)

Verified step by step guidance

1. Understand the factors that influence population size: Population size is affected by four main factors: birth rate, death rate (mortality), immigration (individuals moving into the population), and emigration (individuals leaving the population).
2. Analyze the impact of each factor: Increased emigration and higher mortality rate both result in individuals leaving the population or dying, which decreases population size. Similarly, a lower birth rate means fewer individuals are being added to the population, also leading to a decrease in size.
3. Consider the role of immigration: Immigration refers to individuals moving into a population. Increased immigration adds more individuals to the population, which would cause the population size to increase rather than decrease.
4. Identify the factor that does NOT decrease population size: Based on the analysis, increased immigration is the only factor listed that would not cause a population size to decrease.
5. Conclude the reasoning: Increased immigration contributes positively to population size, while the other factors (increased emigration, higher mortality rate, and lower birth rate) contribute negatively to population size.