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: Anaesthesia
[{'content': 'Foleys catheter 16 F means \nSelect and explain. \nA. 16 mm inner diameter, B. 16 mm outer diameter, C. 16 mm circumference, D. 16 mm for 16 years old', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 16 mm outer diameter', 'role': 'assistant'}]