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': 'What is the established vertical dimension freeway space \nin millimeters? \nSelect and explain. \nA. 6-May, B. 3-Jan, C. 4-Feb, D. 8-Jun', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]