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': 'If the nib diameter is reduced by half, the compaction force is \nSelect and explain. \nA. Halved, B. double, C. Increases 4 times, D. constant', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]