This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
All organisms shows bipolar staining except - 
Select and explain. 
A. Calymmatobacter granulomatis, B. Y. pestis, C. Pseudomonas mallei, D. H. influenzae
D: H. influenzae
Answer: D: H. influenzae 
Explanation: Ans. is 'd' i.e., H. influenzae Bipolar staining (safety pin appearance)o Some bacteria display a safety pin appearance due to the accumulation of dye at the poles of the cells,o This characteristic is called bipolar staining.o Bacteria showing bipolar staining are-1. Calymmatobacter granulomatis (Donovani granulomatis)4. Vibrio parahemolyticus2 Pseudomonas mallei5. Yersinia pestis3. Pseudomonas pseudomallei6. H. ducreyi