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
All decrease CO2 absorption in circuit except 
Select and explain. 
A. Resistance in circuit, B. Flow, C. Dead Space, D. Tidal Volume
A: Resistance in circuit
Answer: A: Resistance in circuit 
Explanation: A i.e. Resistance in circuit 3 times of minute volumeQ volumeQ " v:shapes="_x0000_s1027">CO2 absorbers increase circuit resistanceQ. Granule size is a compromise between high resistance & high absorptive surface area of small granules and lower resistance to gas & lesser absorptive surface area of larger granules (d/t channeling)Q Flow rate &tidal volume should not exceed the air space between absorbent granules; this will decrease CO2 absorption.Q The pa of tidal volume that does not undergo alveolar ventilation is referred as dead space; so any increase in dead space decreases CO2 absorption.