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: Dental
Which one of the following species of streptococci is usually not found in human dental plague. 
Select and explain. 
A. S.mutans, B. S.sanguis, C. S.pyogens, D. S.salivarius
C: S.pyogens
Answer: C: S.pyogens 
Explanation: None