This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Family Planning, Subject name: Social & Preventive Medicine
[{'content': 'True about pearl index: \nSelect and explain. \nA. Population study, B. Family planning, C. Contraceptive methods, D. Contraceptive failure', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. (d) Contraceptive failureRef: Park's PSM 21sted. 1472* Pearl index is used to measure the contraceptive efficacy/ contraceptive failure.* It is defined as the number of failures per 100 women- years (HWY) of exposure.P/ =Total accidental pregnancies------------------------Total months of exposurex 1200* Another method used to measure contraceptive failure/ efficacy is life table analysis.* Life table analysis: calculates failure rates for each month of use.", 'role': 'assistant'}]