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
Which single factor could contribute most of the
development of simple gingivitis in children? 
Select and explain. 
A. High fever, B. Poor oral hygiene, C. Oral habits, D. Physical nature of food ingested
B: Poor oral hygiene
Answer: B: Poor oral hygiene 
Explanation: None