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
Therapeutic index of drug is indicator of: 
Select and explain. 
A. Potency, B. Safety, C. Efficacy, D. All
B: Safety
Answer: B: Safety 
Explanation: Ans. B. SafetyTherapeutic index is ratio of LD50 and ED50. LD50 is defined as lethal dose which kill 50 % animals who are given the dose. ED50 is defined as effective dose which is effective in 50 % of the population. It is also known as margin of safety.