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': 'The 5th key to normal occlusion is: \nSelect and explain. \nA. Molar interarch relationship, B. Mesiodistal crown angulations, C. Absence of rotation, D. Tight contacts', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]