This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
Normal diffusion of CO2 at rest 
Select and explain. 
A. 20-25 ml/min, B. 50-100 ml/min, C. 100-200 ml/min, D. 400-500 ml/min
D: 400-500 ml/min
Answer: D: 400-500 ml/min 
Explanation: Normal diffusion capacity of co2 is about 400 to 500 ml per minute Ref: guyton and hall textbook of medical physiology 12 edition page number:350,351,352