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': 'Which of the following periodontal probes has a ball at its tip? \nSelect and explain. \nA. Marquis, B. WHO, C. Michigan, D. UNC-15', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]