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 grouping of streptococci is done by using- \nSelect and explain. \nA. M Protein, B. Group C peptidoglycan cell wall, C. Group C carbohydrate antigen, D. Staining properties', 'role': 'user'}, {'content': 'Answer: C \nExplanation: β hemolytic Streptococcus is classified to group A-V based on C carbohydrate antigen (Lancefield classification)\nM protein is used to further classify group A Streptococcus (Griffith typing).\n\nRef: Apurba Sastry’s Essentials of Medical Microbiology 1/e p221, Ananthanarayan\xa09/e p209', 'role': 'assistant'}]