Cross sectional study
Randomized Control Trials
Ans. A.Cohort Study
The image represents the Natural history of disease that refers to the progression of a disease process in an individual over time, in the absence of treatment.
The timeline shows the state of susceptibility, exposure, the subclinical disease in which pathologic changes take place, the onset of symptoms, followed by the usual time of diagnosis, clinical disease, followed by recovery, disability, or death.
Longitudinal studies are used to study the natural history of the disease.