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': 'When Class III elastics are used, the maxillary first molars will: \nSelect and explain. \nA. Move distally and intrude, B. Move mesially and extrude, C. Move mesially and intrude, D. Move only mesially; there will be no movement in the vertical direction', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Class III elastics are worn from the maxillary first molars to the mandibular canines. The force system created by Class III elastics will produce mesial movement and extrusion of the maxillary first molars.', 'role': 'assistant'}]