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': 'Pearl Index is - \nSelect and explain. \nA. Accident pregnancy per per 1 women year of contraception exposure, B. Accident pregnancy per per 10 women year of contraception exposure, C. Accident pregnancy per per 100 women year of contraception exposure, D. Accident pregnancy per per 1000 women year of contraception exposure', 'role': 'user'}, {'content': "Answer: C \nExplanation: park's textbook of preventive and social medicine 23rd edition. *pearl index is defined as the no of tailers per 100 women -years of exposure", 'role': 'assistant'}]