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': 'Minimum thickness of tissue conditioners should be \nSelect and explain. \nA. 2 mm, B. 1mm, C. 1.5 mm, D. 3 mm', 'role': 'user'}, {'content': 'Answer: B \nExplanation: For these materials to be effective, a thickness of 1 mm or more is required. A new application is required every three to four days, till tissues have recovered. Proper P:L ratio should be followed to derive maximum benefit from their use.', 'role': 'assistant'}]