Explanation:

The Least Developed Countries (LDC) is a list of the countries that, according to the United Nations, exhibit the lowest indicators of socioeconomic development, with the lowest Human Development Index ratings of all countries in the world. The concept of LDCs originated in the late 1960s and the first group of LDCs was listed by the UN in its resolution 2768 (XXVI) of 18 November 1971. A country is classified among the Least Developed Countries if it meets three criteria
•    Poverty – adjustable criterion based on GNI per capita averaged over three years. As of 2015 a country must have GNI per capita less than US $1,035 to be included on the list, and over $1,242 to graduate from it.
•    Human resource weakness (based on indicators of nutrition, health, education and adult literacy) and
•    Economic vulnerability (based on instability of agricultural production, instability of exports of goods and services, economic importance of non-traditional activities, merchandise export concentration, handicap of economic smallness, and the percentage of population displaced by natural disasters)
LDC criteria are reviewed every three years by the Committee for Development Policy (CDP) of the UN Economic and Social Council (ECOSOC). Countries may "graduate" out of the LDC classification when indicators exceed these criteria.