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': 'According to Melcher concept, the regeneration of new attachment is from \nSelect and explain. \nA. periodontal ligament, B. gingival connective tissue, C. alveolar bone, D. junctional epithelium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]