The correct answer is C. Per capita income.
The Human Development Index (HDI) is a composite statistic of life expectancy, education, and per capita income indicators, which are used to rank countries into four tiers of human development. A country scores higher if it performs better on these indicators.
Life expectancy is the average number of years that a newborn is expected to live if current mortality rates continue to apply. Education is measured by two indicators: mean years of schooling and expected years of schooling. Per capita income is the gross national income (GNI) per capita, converted to international dollars using purchasing power parity (PPP).
Per capita income is not included in the HDI because it is a measure of economic development, not human development. Economic development is important, but it is not the only measure of a country’s well-being. The HDI also takes into account life expectancy and education, which are important measures of human development.
Life expectancy is a measure of how long people are expected to live. It is a good indicator of the quality of health care and the overall health of a population. Education is a measure of the level of knowledge and skills that people have. It is a good indicator of the level of opportunity and the quality of life in a country.
The HDI is a useful tool for comparing the well-being of countries. It is also a useful tool for tracking progress over time. The HDI has been criticized for being too simplistic and for not taking into account all aspects of human development. However, it is still a valuable tool for understanding the state of human development in the world.