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 value of C-factor for class IV composite restoration is \nSelect and explain. \nA. 0.25, B. 0.5, C. 1, D. 2', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]