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 cause of chronic inflammation of the gingiva in a preschool child 
Select and explain. 
A. Acute herpetic gingivostomatitis, B. Acute necrotising gingivitis, C. Apthous stomatitis, D. Vitamin B deficiency
A: Acute herpetic gingivostomatitis
Answer: A: Acute herpetic gingivostomatitis 
Explanation: None