Correct Option: D. Improvement in transportation Explanation of the Correct Answer To understand why "improvement in transportation" is the least significant factor explaining the fast-growing population in Africa, we need to analyze each option in the context of population growth dynamics.

1. Control of Diseases (Option A):
2. Impact: The control of diseases, particularly infectious diseases such as malaria, HIV/AIDS, and tuberculosis, has a direct impact on population growth. When diseases are controlled, mortality rates decrease, leading to a higher life expectancy and a growing population.
3. Mechanism: Improved healthcare, vaccination programs, and public health initiatives have significantly reduced the death rates in many African countries. This has allowed more people to survive into adulthood and contribute to population growth.
4. Decline in Death Rate (Option B):
5. Impact: A decline in the death rate is a crucial factor in population growth. As healthcare improves and living conditions enhance, fewer people die from preventable causes.
6. Mechanism: Factors such as better nutrition, access to clean water, and advancements in medical care contribute to lower mortality rates. This leads to a natural increase in population as the birth rate often remains high while the death rate falls.
7. The Education of Women (Option C):
8. Impact: The education of women is a significant factor influencing population growth, but its effects can be complex. While education often leads to lower birth rates in the long term, it also empowers women to make informed choices about family planning.
9. Mechanism: Educated women tend to have fewer children, but they also tend to have children later in life. In the short term, as more women gain access to education, there may be a temporary increase in population growth as they enter the workforce and delay childbirth.
10. Improvement in Transportation (Option D):
11. Impact: While improved transportation can facilitate economic growth and access to resources, it does not directly influence population growth in the same way that health and education do.
12. Mechanism: Transportation improvements can lead to better access to markets, healthcare, and education, but they do not inherently increase birth rates or decrease death rates. Therefore, while they may support population growth indirectly by enhancing economic opportunities, they are not a primary driver of population increase.

Why the Other Options Are Stronger

• Options A, B, and C all directly relate to factors that influence mortality and fertility rates, which are the primary determinants of population growth. They address the health and social conditions that lead to a higher number of births and a lower number of deaths, which are essential for understanding demographic changes.
• Option D, on the other hand, is more about infrastructure and economic development rather than direct demographic factors. While it can support population growth indirectly, it does not explain the rapid increase in population as effectively as the other options.

Summary of Key Points

• Control of diseases and decline in death rates are critical for reducing mortality and increasing life expectancy, leading to population growth.
• Education of women can influence birth rates, empowering women to make informed reproductive choices, though it may lead to a temporary increase in population as women enter the workforce.
• Improvement in transportation does not directly affect birth or death rates and is therefore the least relevant factor in explaining fast population growth in Africa.
• Understanding the interplay of health, education, and economic factors is essential for grasping the dynamics of population changes.

Revision Summary

• Population growth in Africa is primarily driven by health improvements and education.
• Control of diseases and a decline in death rates are key factors in increasing life expectancy.
• Education of women influences reproductive choices and can lead to changes in birth rates.
• Improvement in transportation, while beneficial, is the least significant factor in explaining rapid population growth.