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
The factor responsible for the left shift of HbO2 dissociation curve is 
Select and explain. 
A. Increase in 2,3 DPG in RBC, B. Fall in temp, C. Fall in pH, D. Increase level of CO2 in blood
B: Fall in temp
Answer: B: Fall in temp 
Explanation: None