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: Anaesthesia
Lancefield grouping of streptococci is done by using? 
Select and explain. 
A. M Protein, B. Group C peptidoglycan cell wall, C. Group C carbobydrate antigen, D. Staining propeies
C: Group C carbobydrate antigen
Answer: C: Group C carbobydrate antigen 
Explanation: Ans. is 'c' i.e., Group C carbohydrate antigen