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
A 2½ year old child with severe horizontal bone resorption and normal cementum is suffering from? 
Select and explain. 
A. Hypophosphatasia, B. Precocious periodontosis, C. Down syndrome, D. Generalized periodontitis
B: Precocious periodontosis
Answer: B: Precocious periodontosis 
Explanation: None