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': 'Total arch length reduced due to mesial migration of teeth? \nSelect and explain. \nA. 1 cm, B. 3 cm, C. 0.5 cm, D. 0.15 cm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]