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
Sharpey's fibres are derived from : 
Select and explain. 
A. Hertwig's root sheath, B. Epithelial rests of malassez, C. Alveolar bone, D. Dental follicle
D: Dental follicle
Answer: D: Dental follicle 
Explanation: None