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: Gynaecology & Obstetrics
The best test in diabetic mother to diagnose baby's lung maturity : 
Select and explain. 
A. Phosphatidyl inositol, B. Sphingomyelin/Lecithin ratio, C. Ultrasonography, D. None of the above
A: Phosphatidyl inositol
Answer: A: Phosphatidyl inositol 
Explanation: Phosphatidyl inositol