This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': '100 women, followed up 20 months, with OCPs, 5 became pregnant, Calculate the Pearl Index - \nSelect and explain. \nA. 100, B. 200, C. 300, D. 400', 'role': 'user'}, {'content': 'Answer: C \nExplanation: HWY =Total accidental pregnancies/months of exposure*1200 HWY=5/20*1200= 300 HWY indicates contraceptive efficacy Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 510', 'role': 'assistant'}]