This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
Which of the following stain is used? 
Select and explain. 
A. Methyl violet, B. Brilliant cresyl blue, C. Sudan black, D. Indigo carmine
B: Brilliant cresyl blue
Answer: B: Brilliant cresyl blue 
Explanation: This is a form of supravital staining in which cells are stained while living. It takes two days from reticulocytes to become RBC Ref : 12-14