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
According to Melcher concept, the regeneration of new attachment is from 
Select and explain. 
A. periodontal ligament, B. gingival connective tissue, C. alveolar bone, D. junctional epithelium
A: periodontal ligament
Answer: A: periodontal ligament 
Explanation: None