This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Koplik spots is a feature of - \nSelect and explain. \nA. Rubella, B. Measles, C. Tetanus, D. Mumps', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Presence of Koplik&;s spot is pathognomic of measles. They are like table salt crystals appear on buccal mucosa opposite the first and second lower molars. Ref: PARK&;S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 23rd edition pg 147', 'role': 'assistant'}]