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
Which is the best parameter for analysis of Hypoxic hypoxia: 
Select and explain. 
A. Aerial PO2, B. Aerial PCO2, C. Venous PO2, D. A-V Difference
A: Aerial PO2
Answer: A: Aerial PO2 
Explanation: A i.e. Aerial PO2.