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': 'In an epidemic first to be done is- \nSelect and explain. \nA. Identity the cases, B. Confirm the diagnosis, C. Identify the prone people, D. Identify the causative factors', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]