This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
[{'content': 'A gamma nerve diameter is \nSelect and explain. \nA. 13-20, B. 13-Apr, C. 6-Mar, D. 0.2-1.0', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A delta fibre diameter is 3-6 um. Ref: Ganong&;s review of medical physiology; 23rd edition; pg: 89; table 4-1.', 'role': 'assistant'}]