This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Dermatitis, Subject name: Dental
[{'content': 'Most common precipitant of contact dermatitis is - \nSelect and explain. \nA. Gold, B. Nickel, C. Silver, D. Iron', 'role': 'user'}, {'content': 'Answer: B \nExplanation: nickel is the most common sensitisers all over the world. the prevelance of nickel sensitivity varies from 4-13%. nickel produces allergic contact dermatitis. clinical presentation: exudative eczema, nummular eczema or dry lichenified eczema. lesions appear beneath earrings, bracelets, bangles, hairpins, rings, wrist watches,safetypins, buttons, stethoscopes. IADVL textbook of dermatology, contact dermatitis page 559', 'role': 'assistant'}]