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
Ultrasound can detect CVS /cardiac activity at : 
Select and explain. 
A. 5-6 weeks, B. 6-7 weeks, C. 7-8 weeks, D. 8-10 weeks
A: 5-6 weeks
Answer: A: 5-6 weeks 
Explanation: 5-6 weeks