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': 'Which one of the following may NOT be used during the\nflanking of dentures: \nSelect and explain. \nA. petroleum, B. tin foil, C. tin foil substitute, D. silicone lubricant', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]