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
In class III composite preparation, retention points should be placed: 
Select and explain. 
A. In the axial wall, B. Entirely in dentine, C. At the dentinoenamel junction, D. At the expense of facial and lingual wall
B: Entirely in dentine
Answer: B: Entirely in dentine 
Explanation: None