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: Pathology
[{'content': 'Protective species or non cariogenic bacteria among the following is/are: \nSelect and explain. \nA. Veillonella., B. Capnocytophega., C. Streptococcus mitis., D. Both AB', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]