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
What is common in class I cavity preparation for amalgam and gold inlay? 
Select and explain. 
A. Buccolingually divergent walls, B. Mesiodistally divergent walls, C. Maximum depth is needed in both cases to provide sufficient thickness, D. All of the above
B: Mesiodistally divergent walls
Answer: B: Mesiodistally divergent walls 
Explanation: None