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
The component responsible for allergy in dental casting alloys is 
Select and explain. 
A. Cobalt, B. Nickel, C. Copper, D. Titanium
B: Nickel
Answer: B: Nickel 
Explanation: 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.
Ref: Phillip’s 12th edition page 127.