A society enters a phase where mortality declines sharply because of improvements in public health, but fertility patterns remain largely unchanged. What is the most likely demographic consequence?

A widening gap between birth and death rates leading to rapid population growth.

The correct answer is Option 2: A widening gap between birth and death rates leading to rapid population growth.

In the transitional stage of demographic transition, death rates decline rapidly due to improvements in public health, disease control, sanitation, and nutrition. However, birth rates remain high because reproductive behaviour changes more slowly. As a result, the gap between birth rates and death rates widens, producing a period of very rapid population growth often referred to as a population explosion.

Option 1: A narrowing gap between birth and death rates leading to population stability. Incorrect. During the transitional stage, the gap widens rather than narrows because death rates fall faster than birth rates.

Option 2: A widening gap between birth and death rates leading to rapid population growth. Correct. This is the defining demographic consequence of the transitional stage.

Option 3: A simultaneous decline in births and deaths resulting in zero population growth. Incorrect. The theory specifically states that birth rates do not decline as quickly as death rates during this stage.

Option 4: A decline in population as mortality reduction encourages smaller family size. Incorrect. Mortality reduction initially leads to faster population growth, not population decline. Family-size preferences generally take longer to change.