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': 'Fluid flow, in or out of the dentinal tubules proportional to the tuble diameter by \nSelect and explain. \nA. Third power of the diameter, B. Sixth power of the diameter, C. Square of the diameter, D. Fourth power of the diameter', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]