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': 'Leprosy commonly spreads by: \nSelect and explain. \nA. Milk, B. Droplet, C. Water, D. Mosquitoes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Droplet', 'role': 'assistant'}]