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': "Most accurate method of diagnosis of pregnancy at 6 weeks: AIIMS 13; JIPMER 14 \nSelect and explain. \nA. Hegar's sign, B. X-ray examination, C. Palpation of fetal pas, D. Fetal hea sound by USG", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Fetal hea sound by USG', 'role': 'assistant'}]