This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
Liley curve for evaluation of amnionic fluid bilirubin in Rh sensitized patient stas at 
Select and explain. 
A. 14weeks, B. 16weeks, C. 20weeks, D. 26weeks
D: 26weeks
Answer: D: 26weeks 
Explanation: The main limitation of the liley curve is that it stas at 26weeks gestation and extrapolation of the lines to earlier gestational ages is inaccurate. Queenan has developed a curve for fetal assessment from 14-40weeks, divided into 4zones