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
Most common age for incidence of gingivitis in children 
Select and explain. 
A. 1 - 3 yrs, B. 11 - 13 yrs, C. 6 - 7 yrs, D. 2 - 7 yrs
C: 6 - 7 yrs
Answer: C: 6 - 7 yrs 
Explanation: None