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': 'All of the following are analytical epidemiological studies except- \nSelect and explain. \nA. Coho study, B. Case - control study, C. Ecological study, D. Field trial', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Analytical studies include: Ecological or correlational-with populations as a unit of study Cross-sectional or prevalence-with individuals as a unit of study Case-control or case reference-with individual as a unit of study Coho or followup-with individual as a unit of study (refer pg no:62 park 23rd edition)', 'role': 'assistant'}]