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
True about Rotameter: 
Select and explain. 
A. Rotameter reading may not get affected by di inside the tube, B. Rotameter reading may not get affected by static electricity, C. The height to which bobbin rises indicates the flow rate, D. A rotameter is a variable pressure flowmeter
C: The height to which bobbin rises indicates the flow rate
Answer: C: The height to which bobbin rises indicates the flow rate 
Explanation: C i.e. The height to which bobbin rises indicates the flow rate