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': 'What is not true about point source epidemic ? \nSelect and explain. \nA. Plateau phase, B. No secondary waves, C. Explosive epidemic, D. Only one peak', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]