The correct answer is: All of the above.
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’s HDI value is a summary measure of its achievements in key areas of human development: a long and healthy life, being knowledgeable, and having a decent standard of living.
The health component of the HDI is based on life expectancy at birth, which is a measure of the average number of years that a newborn is expected to live if current mortality rates continue to apply. Access to healthcare is a measure of the availability of quality healthcare services to the population. Nutrition is a measure of the availability of food and the nutritional status of the population.
All of these factors contribute significantly to a country’s health status and, therefore, to its HDI value.