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: Radiology
Estimation of foetal maturity by hiparietal sonic measurement is accurate to within + -: 
Select and explain. 
A. 3-7 days, B. 7-10 days, C. 10-15 days, D. 14-20 days
A: 3-7 days
Answer: A: 3-7 days 
Explanation: Ans. 3-7 days