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': 'Rat is involved in: \nSelect and explain. \nA. Measles, B. Tetanus, C. Mumps, D. Leptospirosis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Leptospirosis', 'role': 'assistant'}]