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
Rotameters 
Select and explain. 
A. 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
B: Will only function when upright
Answer: B: Will only function when upright 
Explanation: Rotameters are constant pressure drop-variable orifice devices. They are accurate at values as low as 200mL/min both laminar and turbulent flow determine their accuracy .