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 tooth brushing method least likely to remove plaque in the gingival margin is the: \nSelect and explain. \nA. Sulcular method, B. Scrub method, C. Modified stillman, D. Roll stroke', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]