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
Oxygen Hb dissociation curve: Inulin clearance closely resembles: 
Select and explain. 
A. GFR, B. Renal plasma flow, C. Creatinine clearance, D. PAH clearance
A: GFR
Answer: A: GFR 
Explanation: GFR