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
In smokers the incidences of periodontal disease are: 
Select and explain. 
A. 2-6 times, B. 6-10 times, C. 10-14 times, D. No effect
A: 2-6 times
Answer: A: 2-6 times 
Explanation: None