This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 2, Subject name: Physiology
Of the total oxygen consumed by the body (per min.), greatest fraction is consumed by: 
Select and explain. 
A. Liver, B. Brain, C. Muscle, D. kidney
A: Liver
Answer: A: Liver 
Explanation: Under resting conditions, total O2 consumption by the body = 250 ml/min. Greatest fraction of this O2 consumption is by the liver Liver - 30% or 75 ml/min. Muscle consumes 20% or 50 ml/min. Brain consumes 18% or 45 ml/min. In terms of per 100 gm of tissue per min., highest O2 consumption is by the hea - 8 ml/100 gm/min.