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': 'According to ADA specification of toothbrush width of brush head should be: \nSelect and explain. \nA. 5/8-3/8inches., B. 5/16-3/8inches., C. 5/8-3/16inches., D. 5/16-3/16inches.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Length of brush head: 1-1.25 inches.\nWidth of brush head: 5/16-3/2 inches.\nBristles: 2-4 rows.\nTufts in a row: 5-12 tufts', 'role': 'assistant'}]