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
First clinical sign of localized juvenile periodontitis is 
Select and explain. 
A. Tooth mobility, B. Gingival bleeding, C. Pathologic migration, D. Vertical bone loss along incisors and molars
C: Pathologic migration
Answer: C: Pathologic migration 
Explanation: None