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
[{'content': 'Which one of the following species of streptococci is usually not found in human dental plague. \nSelect and explain. \nA. S.mutans, B. S.sanguis, C. S.pyogens, D. S.salivarius', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]