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': 'Anterior openbite & maxillary constriction is caused by: \nSelect and explain. \nA. Thumb sucking, B. Nail biting, C. Bruxism, D. Lip biting', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]