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': 'The major disadvantage of treatment using a cervical head gear is \nSelect and explain. \nA. Impaction of maxillary canines, B. Extrusion of maxillary incisors, C. Extrusion of maxillary molars, D. Deformity of neck', 'role': 'user'}, {'content': 'Answer: C \nExplanation: So cervical head gear is used in patients with low mandibular plane angle and deep bite.', 'role': 'assistant'}]