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
Sex determination in early pregnancy Is done by: 
Select and explain. 
A. X-rays, B. Amniocentesis, C. Ultrasound, D. Hysteroscopy
C: Ultrasound
Answer: C: Ultrasound 
Explanation: Ultrasound