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': 'Bacteria, which are not found in normal healthy periodontium, are: \nSelect and explain. \nA. Actinomyces, B. Capnocytophaga, C. Veillonella, D. Eubacterium', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]