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: Radiology
[{'content': 'Normal metacarpal index is: \nSelect and explain. \nA. Less than 5.4, B. 5.4 to 7.9, C. 8.4 to 10.4, D. More than 10.4', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. 5.4 to 7.9', 'role': 'assistant'}]