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
According to Bennett's classification, abnormal formation of a part or whole of either arch due to developmental defects of bone is: 
Select and explain. 
A. Class 1, B. Class 2, C. Class 3, D. Class 4
B: Class 2
Answer: B: Class 2 
Explanation: Bennett's Classification