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
Pearl Index is - 
Select and explain. 
A. 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
C: Accident pregnancy per per 100 women year of contraception exposure
Answer: C: Accident pregnancy per per 100 women year of contraception exposure 
Explanation: 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