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': "Patients with Down's syndrome normally have: \nSelect and explain. \nA. IQ score above 80, B. Brachycephalic skull, C. Stiff muscles, D. All of the above", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]