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
A 40 year old mine worker is brought to the emergency room with a suspected carbon monoxide poisoning. What will be expected in the blood ABG? 
Select and explain. 
A. PO2 normal, O2 saturation less with slightly decreased PCO2, B. PO2 less, O2 saturation normal, C. PO2 high, O2 saturation normal, D. PO2 less, O 2 saturation decreased
A: PO2 normal, O2 saturation less with slightly decreased PCO2
Answer: A: PO2 normal, O2 saturation less with slightly decreased PCO2 
Explanation: CO2 has 210 times more affinity to Hb than O2 so O2 saturation is less. PO2 is normal since dissolved O2 is normal.