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': 'To obtain best long term result, which of the\nfollowing procedures for augmentation genioplasty is recommended: \nSelect and explain. \nA. On lay bone graft, B. Injection of silastic gel, C. Insertion of silastic rubber implant, D. Pedicled horizontal sliding osteotomy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]