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: Dental
[{'content': 'Not true about propagated epidemics \nSelect and explain. \nA. Herd immunity present, B. Sharp rise and decrease sharply, C. Person to person transmission, D. Multiple waves of epidemic', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]