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: Medicine
Blood for acid base gas (ABGO analysis in a bottle containing heparin can cause decreased value of - 
Select and explain. 
A. pCO2, B. HCO2, C. pH, D. pO2
C: pH
Answer: C: pH 
Explanation: None