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: Anatomy
[{'content': 'Nerve root for dermatome supplying thumb and index finger: \nSelect and explain. \nA. C6 C7, B. C6 C6, C. C7 C8, D. C5 C6', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. C6 C6', 'role': 'assistant'}]