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
[{'content': 'Gram —ve bacteria stain during gram staining: \nSelect and explain. \nA. Blue color, B. Red color, C. Green, D. Colorless', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]