This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, Subject name: Physiology
Which of the following product is primarily filtered with little secretion or re - absorption in renal tubules? 
Select and explain. 
A. Sodium, B. Creatinine, C. Glucose, D. Amino acids
B: Creatinine
Answer: B: Creatinine 
Explanation: Ans. (b) Creatinine(Ref: Ganong, 25th ed/p.679)Substances like inulin and creatinine are useful to estimate GFR because they are freely filtered, neither resorbed, nor secreted