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': 'The bacterial flora associated with Juvenile periodontitis is mainly: \nSelect and explain. \nA. Gram +ve aerobic cocci, B. Gram +ve anaerobic cocci, C. Gram -ve aerobic cocci, D. Gram -ve anaerobic cocci', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]