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
Principal fibres of periodontal ligament are attached to 
Select and explain. 
A. Alveolar bone proper, B. Bundle bone, C. Lamellar bone, D. Cortical bone
B: Bundle bone
Answer: B: Bundle bone 
Explanation: None