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
Pearl index is defined as 
Select and explain. 
A. Accidental pregnancies per 1000 women-years of exposure, B. Accidental pregnancies per 100 women-years of exposure, C. Accidental pregnancies per 10 women-years of exposure, D. Accidental pregnancies per women-years of exposure
B: Accidental pregnancies per 100 women-years of exposure
Answer: B: Accidental pregnancies per 100 women-years of exposure 
Explanation: None