This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ULTRASOUND, Subject name: Radiology
Fetal cardiac activity can be detected earliest by USG at which age of Intrauterine life- 
Select and explain. 
A. 1-2 week, B. 2-4 week, C. 5-6 week, D. 6-8 week
C: 5-6 week
Answer: C: 5-6 week 
Explanation: Fetal cardiac activity can be detected earliest by USG at 5-6-week age of intrauterine life.