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': 'Lancefield classification is used for: \nSelect and explain. \nA. Streptococci and based on protein, B. Streptococci and based on carbohydrate, C. Staphylococci and based on protein, D. Gonococci and based on protein', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Streptococci and based on carbohydrate', 'role': 'assistant'}]