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
With a fixed performance mask such as a ventimask 
Select and explain. 
A. Rebreathing is possible, B. Plugging side holes increases the oxygen concentration, C. Total gas flow is higher than the patient’s peak inspiratory flow, D. There is high equipment dead space
C: Total gas flow is higher than the patient’s peak inspiratory flow
Answer: C: Total gas flow is higher than the patient’s peak inspiratory flow 
Explanation: Dead space in ventimask is low and rebreathing is not possible because of high flow of gas.