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
Pulmonary lymph flow rate is 
Select and explain. 
A. 20 ml/hour, B. 40 ml/hour, C. 50 ml/hour, D. 60 ml/hour
A: 20 ml/hour
Answer: A: 20 ml/hour 
Explanation: Pulmonary lymph flow rate is 20 ml per hour Ref: guyton and hall textbook of medical physiology 12 edition