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
Higher hematocrit in venous blood than in arterial blood is due to 
Select and explain. 
A. High chloride in RBC, B. High Na+ in plasma, C. High HCO3- in plasma, D. High K+ in RBC
A: High chloride in RBC
Answer: A: High chloride in RBC 
Explanation: In venous blood, Cl- moves into RBC which results in fluid shift into RBC. This results in higher hematocrit.