Answer:
1. pandemic - an infectious disease outbreak
2. World Health Organization - an agency of the United Nations
3. social services - government-sponsored services
4. developing countries - low- and middle-income countries
Explanations:
2. The World Health Organization is a specialized agency of the United Nations responsible for international public health. The WHO Constitution, which establishes the agency's governing structure and principles, states its main objective as "the attainment by all peoples of the highest possible level of health". It is headquartered in Geneva, Switzerland, with six semi-autonomous regional offices and 150 field offices worldwide.
3. Social services are a range of public services intended to provide support and assistance towards particular groups, which commonly include the disadvantaged. They may be provided by individual actors, private and independent organizations, or administered by a government agency. Social services are connected with the concept of welfare and the welfare state, as countries with large welfare programs often provide a wide range of social services.
4. There is also no clear agreement on which countries fit this category. The term low and middle-income country (LMIC) is often used interchangeably but refers only to the economy of the countries. The World Bank classifies the world's economies into four groups, based on Gross National Income per capita: high, upper-middle, lower-middle, and low income countries.