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': 'A single force is applied to the crowns of the upper incisors.\nTipping is around the point of rotation present at: \nSelect and explain. \nA. Infinity, B. Apical 1/3rd, C. middle 1/3rd, D. Coronal 1/3rd', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]