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': 'The component responsible for allergy in dental casting alloys is \nSelect and explain. \nA. Cobalt, B. Nickel, C. Copper, D. Titanium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Nickel is the most allergenic metal known, with an incidence of allergic reactions between 10% and 20%. Reactions to nickel are more common among women, presumably because of the chronic exposure to nickel through jewellery.\nRef: Phillip’s 12th edition page 127.', 'role': 'assistant'}]