Between which groups does socio-economic disparity exist?

The correct answer is D. People and groups of people.

Socio-economic disparity refers to the unequal distribution of resources, opportunities, and privileges among individuals or groups in society. It often exists between different social classes, ethnic groups, or communities, indicating that the disparity is not limited to individual differences but rather encompasses larger collective groups. If you have more questions or need further clarification, feel free to ask!