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 is not an instrument grasp during scaling procedure? \nSelect and explain. \nA. Pen grasp, B. Thumb grasp, C. Modified pen grasp, D. Palm and thumbgrasp', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]