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
Periodontal tissue destruction apically and potentially migrating towards the gingival margin is called 
Select and explain. 
A. Marginal periodontitis, B. Marginal Gingivitis, C. Retrograde Periodontitis, D. chronic destructive periodontitis
C: Retrograde Periodontitis
Answer: C: Retrograde Periodontitis 
Explanation: None