This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetus Placenta & Fetal Membrane, Subject name: Gynaecology & Obstetrics
Fetal sex can be detected by USG at: 
Select and explain. 
A. 14 weeks, B. 16 weeks, C. 18 weeks, D. 20 weeks
A: 14 weeks
Answer: A: 14 weeks 
Explanation: Ans. is a, i.e. 14 weeksRef. William's 23/e, p 79"Gender can be determined by experienced observers by inspection of the external genitalia by 14 weeks".Ref Williams Obs 23/e, p 79