This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
What is the clearance of a substance, if its concentration in plasma is 10 mg%, concentration in urine is 100 mg% and urine flow is 2 ml/min? 
Select and explain. 
A. 0.02 ml/min, B. 0.2 ml/min, C. 2 ml/min, D. 20 ml/min
D: 20 ml/min
Answer: D: 20 ml/min 
Explanation: Ans. D. 20ml/min.rate of elimination = amount of drug excreted per hour concentration in urine x urine flow 2mg/min = 100 mg% x 2 ml/minNow Cl = RoE/Plasma concentration Therefore, Clearance =2mg/min/10mg%=20ml/min.