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': 'Mercapton groups are seen in \nSelect and explain. \nA. Polysulphide, B. Addition silicone, C. Condensation silicone, D. Polyether', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]