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: Unknown
[{'content': 'Following strain used is ? \nSelect and explain. \nA. Methyl violet, B. Brilliant cresyl blue, C. Sudan black, D. Indigo carmine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: This is a form of supravital staining in which cells are stained while living. It takes two days from reticulocytes to become RBC', 'role': 'assistant'}]