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
Cavities beginning in the proximal surfaces of bicuspids and molars are 
Select and explain. 
A. Class 1, B. Class 2, C. Class 4, D. Class 6
B: Class 2
Answer: B: Class 2 
Explanation: None