Which of the following developments best explains why mortality rates usually decline before fertility rates during demographic transition?

Medical and public health improvements can be implemented faster than social and reproductive change.

The correct answer is Option 2: Medical and public health improvements can be implemented faster than social and reproductive change.

The theory argues that disease control, public health measures, and improved nutrition can reduce mortality relatively quickly. Changes in reproductive behaviour take longer because they are embedded in social practices and expectations.

Option 1: Families immediately adjust reproductive behaviour whenever life expectancy increases. Incorrect. The theory specifically argues that such adjustment takes time.

Option 2: Medical and public health improvements can be implemented faster than social and reproductive change. Correct. This creates the gap responsible for rapid population growth.

Option 3: Fertility rates are controlled directly by advances in disease control. Incorrect. Disease control primarily affects mortality.

Option 4: Mortality rates decline only after fertility rates have already fallen. Incorrect. The theory suggests the opposite sequence.