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
Physiological changes during severe exercises are all except 
Select and explain. 
A. Hyperventilation in the beginning, B. Hyperkalemia, C. Decreased pa O2, D. Decreased pa CO2
C: Decreased pa O2
Answer: C: Decreased pa O2 
Explanation: None