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 true about cementum 
Select and explain. 
A. It forms a part of periodontium and is avascular., B. Its function is to attach tooth to PDL., C. It provides anchorage to the tooth., D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None