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': 'A boy with skin ulcer on the leg, culture reveals beta hemolysis. Cultures from school children with a sore throat some days back also revealed beta hemolysis. What is the similarity between both \nSelect and explain. \nA. Mec A gene is related to it, B. M protein is same, C. C carbohydrate antigen is same, D. Strains causing both are same', 'role': 'user'}, {'content': "Answer: C \nExplanation: CARBOHYDRATE ANTIGEN: On the basis of the C carbohydrate antigen, S.pyogenes is classified under Lancefield group A. This antigen shows cross-reactivity with some human tissues. This antigen is an integral pa of the cell wall, it has to be extracted for grouping by precipitin test with group antisera. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; Page no: 212", 'role': 'assistant'}]