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
What is the finding seen earliest in USG : 
Select and explain. 
A. Yolk sac, B. Fetal hea, C. Chorion, D. Placenta
A: Yolk sac
Answer: A: Yolk sac 
Explanation: Ans. is a i.e. Yolk sac Fetal structure Detected by TVS Detected by TAS Gestational sac 4 weeks 5 weeks Yolk sac 5 weeks 7 weeks Cardiac activity 5.1 - 6.5 weeks 8 weeks Embryonic movement 7 weeks