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
Best parameter by USG to assess fetal maturity: 
Select and explain. 
A. Crown rump length at 16 weeks, B. Head circumference at 36 weeks, C. Biparietel diameter at 12 weeks, D. Femur length at 12 weeks
C: Biparietel diameter at 12 weeks
Answer: C: Biparietel diameter at 12 weeks 
Explanation: Ans. Biparietel diameter at 12 weeks