This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Malignancies, Subject name: Pediatrics
Pre-cancerous lesion of bone- 
Select and explain. 
A. Paget disease, B. Chronic osteomyelitis, C. Benign giant cell tumor, D. Ail of above
D: Ail of above
Answer: D: Ail of above 
Explanation: Ans. is 'd' i.e., All of above Pre-cancerous lesion of boneMultiple exostosesOllier's diseaseBenign giant cell tumorOsteoblastomaChondroblastomaChronic osteomyelitisPaget's disease