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 probing pressure applied by CPITN probe \nSelect and explain. \nA. 10 grams, B. 25 grams, C. 35 grams, D. 45 grams', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]