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 children below 5 years of age, most common cause of gingivitis is 
Select and explain. 
A. local irritating factors, B. herpes, C. vitamin deficiency, D. malocclusion
A: local irritating factors
Answer: A: local irritating factors 
Explanation: None