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: Physiology
True regarding conversion of deoxyhemoglobin to oxyhemoglobin is 
Select and explain. 
A. Binding of O2 causes release of H+, B. One mole of deoxyhemoglobin binds two moles of 2,3 DPG, C. pH of blood has no affect on the binding of O2, D. Binding of O2 causes increased binding 2.3,DPG
A: Binding of O2 causes release of H+
Answer: A: Binding of O2 causes release of H+ 
Explanation: When O2 binds to Hb, then the H+ is released.
One mole of 2,3 DPG binds to one mole of deoxyhemoglobin.
O2 carrying capacity of Hb is affected by the change in pH.
When O2 is bound to hemoglobin, 2,3 DPG does not bind to Hb.