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': 'Most of the manufacturers supply the gold foil coated with_____. \nSelect and explain. \nA. Aluminium chloride, B. Ammonium chloride, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: It is coated in order to prevent contamination.', 'role': 'assistant'}]