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: Microbiology
[{'content': 'Safety pin appearance of bacteria is seen in ? \nSelect and explain. \nA. Vibrio cholerae, B. Chlamydia, C. H influenzae, D. Yersinia pestis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]