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': 'Myoplasty and sulcus extension procedures are\nhelpful in: \nSelect and explain. \nA. Increasing retention, B. Increasing stability, C. Increasing support, D. Increasing retention and stability', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]