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: Social & Preventive Medicine
Contraceptive efficacy is assessed by ? 
Select and explain. 
A. Pearl index, B. Chandelers index, C. Quetlet index, D. Broca index
A: Pearl index
Answer: A: Pearl index 
Explanation: Ans. is 'a' i.e., Pearl index