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 coupling agent used in composite resin \nSelect and explain. \nA. Colloidal silica, B. Urethane dimethacrylate, C. Organo silanes, D. Diketones', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]