Which field studies factors affecting the health and illness of populations?

The field that studies factors affecting the health and illness of populations is epidemiology. This discipline focuses on understanding the distribution and determinants of health-related states or events in specific populations. Epidemiologists analyze data to identify risk factors for disease and patterns of health issues within populations, enabling public health officials and policymakers to implement effective interventions and preventive measures.

Epidemiology encompasses various aspects such as investigating outbreaks, studying the effects of environmental exposures, and evaluating health services. The insights gained from epidemiological research are crucial for improving health outcomes and understanding how social, economic, and environmental factors influence the well-being of communities.

In contrast, the other options refer to specific concepts or measurements within health studies. Endemic describes a constant presence and prevalence of a disease within a geographical area, incidence refers to the number of new cases of a disease in a specified time period, and prevalence indicates how many individuals have a particular disease at a specific point in time. While these terms are related to the study of health in populations, they do not encompass the broader investigation of health determinants that is the hallmark of epidemiology.