This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'A disease whose etiology is not known, the first step in the formation of hypothesis will be ? \nSelect and explain. \nA. Cross sectional study, B. Descriptive epidemiology, C. Case control study, D. Coho study', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Descriptive epidemiology Descriptive epidemiology is the first phase of epidemilogical investigation.", 'role': 'assistant'}]