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
Safety pin appearance of bacteria is seen in ? 
Select and explain. 
A. Vibrio cholerae, B. Chlamydia, C. H influenzae, D. Yersinia pestis
D: Yersinia pestis
Answer: D: Yersinia pestis 
Explanation: None