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': 'Lingual fixed appliance is used in \nSelect and explain. \nA. Bilateral loss of 1st molars, B. Bilateral loss of canines, C. Bilateral loss of laterals, D. Unilateral loss of premolars', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]