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': 'Periochip is a commercially available local drug delivery system containing: \nSelect and explain. \nA. Doxycycline, B. Chtorhexidine, C. Minocycline, D. Metronidazole', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]