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: Pharmacology
The clearance of drug means- 
Select and explain. 
A. Unit volume of plasma which is cleared off drug in a unit of time, B. Amount of drug excreted in urine, C. Amout of drug metabolised in unit of time, D. All of the above
A: Unit volume of plasma which is cleared off drug in a unit of time
Answer: A: Unit volume of plasma which is cleared off drug in a unit of time 
Explanation: Ans. is 'a' i.e., Unit volume of plasma which is cleared off drug in a unit of time The clearance of a drug is the theoretical volume of plasma from which the drug is completely removed in unit time.