This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacodynamics, Subject name: Pharmacology
Shelf life of a drug is:- 
Select and explain. 
A. Time from manufacturing date to expiry date, B. The time after which the drug loses its potency, C. Time in which 93% of drug is eliminated, D. The time after which drug become toxic
A: Time from manufacturing date to expiry date
Answer: A: Time from manufacturing date to expiry date 
Explanation: Shelf life: It is the time for which drug can be sold by the pharmacist. It is calculated as time between expiry date and manufacturing date.