Which indicators are used in Human Development Index (HDI) ?
1. Income level
2. Education
3. Condition of environment
4. Life expectancy
Select the correct answer from the codes given below :

The Human Development Index (HDI), published annually by the United Nations Development Programme (UNDP), is a composite statistic used to rank countries by levels of human development. It is based on three main dimensions:

• A long and healthy life: Measured by life expectancy at birth (Indicator 4).
• Knowledge: Measured by education indicators, specifically the mean years of schooling for adults and expected years of schooling for children (Indicator 2).
• A decent standard of living: Measured by income level, specifically Gross National Income (GNI) per capita at purchasing power parity (Indicator 1).

The condition of the environment (Indicator 3) is not a component of the standard HDI calculation. Thus, indicators 1, 2, and 4 are used, making option C the correct answer.