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
Moderate papillary recession with slightly open incremental space is classified as: 
Select and explain. 
A. Class 1 embrasure., B. Class 2 embrasure., C. Class3 embrasure., D. Class4 embrasure.
B: Class 2 embrasure.
Answer: B: Class 2 embrasure. 
Explanation: None