This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in obstetrics, 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: Among the given options,yolk sac will appear early in the USG.It appears at 5 th weeks of gestation. Fetal node appears at 5 and half weeks of gestation,Fetal hea appears or to be felt at 6 weeeks of gestation. Refer page no 475 of Text book of obstetrics,sheila balakrishnan,2 nd edition.