Final answer:
Population growth and fertility rates are lowest in upper-income countries, where economic growth, better healthcare, education, and urbanization contribute to lower birth rates and smaller family sizes.
Step-by-step explanation:
Population growth and fertility rates are generally lowest in upper-income countries. Factors contributing to this trend include increased access to education, particularly for women, improved healthcare systems, and greater economic development. As countries become more economically developed, they often experience lower fertility rates due to a combination of these factors, including family planning and the choice to have fewer children. Evidence of this is seen in high-income nations like most of Europe, where the United Nations Population Fund anticipates population declines of about 20 percent due to low fertility rates. On the other hand, high-fertility countries, mainly in sub-Saharan Africa, expect population growth to triple between 2011 and 2100. Additionally, the transition to a more urban and industrially advanced society generally coincides with smaller family sizes.
In contrast, less economically developed countries, often found in Africa and Asia, have the highest population growth rates due to higher fertility rates. This can be attributed to a variety of socio-economic factors, including limited access to education and family planning resources, as well as cultural norms valuing larger family sizes. Moreover, economically underdeveloped countries tend to have a greater proportion of young individuals compared to developed countries.
Therefore, the correct answer to the student's question is a. upper-income countries.