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
Intrabony defects are 
Select and explain. 
A. one-walled defects, B. two-walled defects, C. three walled defects, D. combination of above
C: three walled defects
Answer: C: three walled defects 
Explanation: None