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
Oxygen dissociation curve shifts to the right by all of the following except: 
Select and explain. 
A. Rise in temperature, B. Rise in carbon dioxide tension, C. Rise in pH, D. Rise in H + ion
C: Rise in pH
Answer: C: Rise in pH 
Explanation: A shift to the left indicates acceptance of oxygen by hemoglobin and the shift to right indicates dissociation of oxygen from hemoglobin. Factors favoring shift to right are —

Decreased PO2
Increased PCO2 (Bohr effect)
Increase in H+ concentration or decreased pH
Excess of 2, 3 DPG (exercise, high altitudes)
Increased body temperature