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
Streptococcus pyogenes shows pathogenicity by all except? 
Select and explain. 
A. M protein, B. Pyrotoxin, C. Pili, D. Streptolysin O
C: Pili
Answer: C: Pili 
Explanation: Ans. is 'c' i.e., Pili Virulence factors of str. pyogenes Str. pyogenes forms several exotoxins and enzymes which contribute to its virulence, but M protein is the most impoant of these.