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: Skin
[{'content': 'Most common precipitant of contact dermatitis is \nSelect and explain. \nA. Gold, B. Nickle, C. Silver, D. Iron', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Nickle', 'role': 'assistant'}]