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': 'Angle between diazone and parazone is: \nSelect and explain. \nA. 30°., B. 40°., C. 45°., D. 50°.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Parazone – dark bands produced by longitudinally cut rods.\nDiazone – Light bands produced by transversely cut rods.\nAngle b/w diazone & parazone = 40°.', 'role': 'assistant'}]