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': 'In case of retreatment which is ideal for removal of G.P.? \nSelect and explain. \nA. H-file, B. K-file, C. GT-file, D. Lentulospiral', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]