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 arch length preservation can be best carried out by: \nSelect and explain. \nA. Placing a lingual arch, B. Restoring carious teeth, C. Placing band and loop space maintainer, D. Placing an acrylic removable space maintainer', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]