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 about Hb dissociation curve is 
Select and explain. 
A. Acidosis shifts O2 dissociation curve to right, B. ↑CO2 shifts the curve to left, C. Hypoxia shifts curve to left, D. 2, 3 DPG has no effect on curve
A: Acidosis shifts O2 dissociation curve to right
Answer: A: Acidosis shifts O2 dissociation curve to right 
Explanation: Hb-O2 dissociation curve shift to left indicates more affinity of Hb to O2, and thus less delivery of O2 to tissues.
Shift to left seen in
-        Increased pH
-        Decreased 2,3 DPG, temperature, PCO2
-        HbF (Fetal)
Shift to right seen in
-        Decreased pH
-        Increased 2,3DPG, temperature, PCO2
-        HbS (Sickle cell)