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 bar is: \nSelect and explain. \nA. Maxillary major connector, B. Direct retainer, C. Indirect retainer, D. None of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]