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
[{'content': 'A localized gingival recession between two teeth in an otherwise healthy 7 year old child, may be due to: \nSelect and explain. \nA. ANUG, B. Abnormal oral habit, C. Chronic gingivitis, D. Herpes simplex', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Any localized gingival recession between two teeth in an otherwise healthy child may give rise to suspicion about abnormal oral habit. \nMany children have habit of stripping the gingival tissue or keeping the nail between two teeth.\nThis activity will cause gingival recession with respect to that tooth and if it is maintained for long duration has an adverse effect on the tooth-supporting structures.', 'role': 'assistant'}]