This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'Experimental studies are meant to - \nSelect and explain. \nA. Test etiological hypothesis, B. Find out prevalence rates, C. Find out cause of epidemics, D. To find out the history of disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Experimental studies involve an active attempt to change a disease determinant or the progress of a disease and are similar in design to experiments in other sciences. The major experimental design is randomized control trials. Field trials and community trials are other experimental studies. (refer pgno:63 park 23 rd edition)', 'role': 'assistant'}]