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
Best investigation to diagnose fetal age is : 
Select and explain. 
A. Serial Ultrasound, B. Amniocentesis, C. Fundal height measurement, D. X-ray
A: Serial Ultrasound
Answer: A: Serial Ultrasound 
Explanation: Serial Ultrasound