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 maximum effect of a drug is defined by- 
Select and explain. 
A. Therapeutic index, B. Potency, C. Efficacy, D. Adversity
C: Efficacy
Answer: C: Efficacy 
Explanation: Ans. is 'c' i.e., Efficacy - Refers to maximal response that can be produced by a drug. Potency - Amount of drug needed to produce a given response.