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': 'Lancefield group of streptococci is based on \nSelect and explain. \nA. M proteins, B. Carbohydrate ( C ) antigen on the cell wall, C. Bile solubility, D. Sugar fermentation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Carbohydrate contained in the cell wall of many streptococci forms the basis of serologic grouping into Lancefield groups A-H and K-U. The serologic specificity of the group-specific carbohydrate is determined by an amino sugar.Jawetz 23e pg: 213', 'role': 'assistant'}]