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
O2 release to tissue is affected by all except 
Select and explain. 
A. 2,3-DPG, B. pH, C. Bicarbonate, D. Globin chain
C: Bicarbonate
Answer: C: Bicarbonate 
Explanation: Ans: c (Bicarbonate) Ref: Ganong 22nd ed/p.667O2 release to tissue depends on oxygen dissociation curve.Shift of oxygen dissociation curve depends upon 2,3 - DPG pH and globin chain.