What do epidemiologists primarily study to understand health issues?

Epidemiologists primarily study patterns of disease to understand health issues because their main focus is on how diseases spread, who is affected, and the factors that influence health outcomes within populations. By analyzing data related to incidence, prevalence, and distribution of diseases, they can identify trends and potential outbreaks. This systematic study enables epidemiologists to derive insights into causal relationships and risk factors, helping to inform public health strategies and interventions aimed at controlling disease and improving health. The other options, while relevant to understanding health, do not capture the primary focus of epidemiology, which is centered on the patterns of disease occurrence and distribution among populations.