The Demographic Transition Theory explains the transition from high birth and death rates to low birth and death rates, accompanied by changes in population growth and age structure.

Total Fertility Rate (TFR) is the average number of children a woman is expected to have during her reproductive years, assuming current age-specific fertility rates remain constant.

The Gender Inequality Index is not a component of the HDI. The HDI consists of Life Expectancy at Birth, Mean Years of Schooling, and Gross National Income per Capita.

Infant Mortality Rate (IMR) is the number of deaths of children under one year of age per 1,000 live births.

Genetics is not considered a determinant of health by the World Health Organization. The main determinants of health are environment, lifestyle, and healthcare system.

Population Explosion refers to a rapid increase in population size, often associated with high birth rates and declining death rates.

Improved Sanitation is not typically associated with rapid population growth. Overcrowding, increased pollution, and the spread of infectious diseases are common challenges.

Carrying Capacity refers to the maximum population size that can be supported by an environment without exceeding its resources and causing environmental degradation.

Decreasing Dependency Ratio is not a common indicator of population aging. Increasing Proportion of Elderly Population, Rising Life Expectancy, and Shrinking Labor Force are common indicators.

Demographic Dividend refers to the economic benefits that can arise from a change in the age structure of a population, typically resulting from a decline in fertility rates.

Improved Life Expectancy is not a common health challenge associated with population aging. Increased Prevalence of Chronic Diseases, Higher Healthcare Costs, and Increased Demand for Long-Term Care are common challenges.

Urbanization refers to the process of population movement from rural to urban areas, resulting in the growth of cities and towns.

Improved Access to Healthcare is not a common health challenge associated with urbanization. Increased Air Pollution, Higher Risk of Obesity, and Spread of Infectious Diseases are common challenges.

Counterurbanization refers to the process of population movement from urban areas to rural areas, often driven by factors such as lifestyle preferences, affordability, and environmental concerns.

Improved Air Quality is not a common health challenge associated with counterurbanization. Limited Access to Healthcare Services, Higher Rates of Chronic Diseases, and Increased Risk of Isolation and Loneliness are common challenges.