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: Surgery
[{'content': 'Skin graft vestibuloplasty prevent relapse by: \nSelect and explain. \nA. Forming a barrier to reattachment of muscle to periosteum, B. Promoting osteogenesis to establish a bone barrier to loss of sulcus depth, C. Causing an inhibitory effect on fibroblasts in the underlying tissue, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]