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
Angle between diazone and parazone is: 
Select and explain. 
A. 30°., B. 40°., C. 45°., D. 50°.
B: 40°.
Answer: B: 40°. 
Explanation: Parazone – dark bands produced by longitudinally cut rods.
Diazone – Light bands produced by transversely cut rods.
Angle b/w diazone & parazone = 40°.