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
which of the following is/are non self cleansable fissure: 
Select and explain. 
A. I, B. K, C. Inverted Y, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None