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: Forensic Medicine
[{'content': 'Transvaginal USG can detect fetal cardiac activity in: DNB 10; MAHE 12 \nSelect and explain. \nA. 5 weeks, B. 6 weeks, C. 7 weeks, D. 8 weeks', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. 5 weeks', 'role': 'assistant'}]