This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Negative staining technique is used for \nSelect and explain. \nA. Mycobacteria, B. Pseudomonas, C. Bacillus, D. Clostridium', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Negative StainingThis procedure involves staining the background with an acidic dye, leaving the cells contrastingly colorless. The black dye nigrosin is commonly used. This method is used for cells or structures that are difficult to stain directly. Used for BacillusRef: Javetz Medical Microbiology; 27th edition; Page no: Page no: 38', 'role': 'assistant'}]