In population demography, which pair of processes can cause a population to decrease in size over time?

• A. Higher natality and immigration
• B. Higher natality and lower emigration
• C. Higher mortality and emigration
• D. Lower mortality and higher immigration

Answer: (C)

Verified step by step guidance

1. Understand the key terms: 'natality' refers to birth rate, 'mortality' refers to death rate, 'immigration' is the arrival of individuals into a population, and 'emigration' is the departure of individuals from a population.
2. Recognize that a population decreases in size when the number of individuals leaving or dying exceeds the number of individuals being added through births or arrivals.
3. Analyze each pair of processes: higher natality and immigration both add individuals, so they would increase population size, not decrease it.
4. Consider that higher mortality (more deaths) and emigration (more individuals leaving) both reduce population size, making this pair capable of causing a population decrease.
5. Conclude that the pair 'higher mortality and emigration' is the correct choice because both processes contribute to a decline in population size over time.