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
Tobacco Chewing/ smoking is the most common predisposing cause of which of the following: 
Select and explain. 
A. Cyclic neutropenia, B. Juvenile periodontitis, C. Necrotising periodontitis, D. Necrotising ulcerative gingivitis (ANUG)
D: Necrotising ulcerative gingivitis (ANUG)
Answer: D: Necrotising ulcerative gingivitis (ANUG) 
Explanation: None