This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
Percentage of women who deliver on expected date of delivery 
Select and explain. 
A. 4%, B. 15%, C. 35%, D. 70%
A: 4%
Answer: A: 4% 
Explanation: EDD is calculated using Naegle's rule