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': 'Rotameters \nSelect and explain. \nA. Depend on laminar low for their accuracy, B. Will only function when upright, C. Are constant pressure drop-constant orifice devices, D. Are not accurate below 1L/min', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Rotameters are constant pressure drop-variable orifice devices. They are accurate at values as low as 200mL/min\xa0both laminar and turbulent flow determine their accuracy .', 'role': 'assistant'}]