This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
[{'content': 'Gas shadow in hea and vessels are seen in \nSelect and explain. \nA. IUD, B. Still bih, C. Aboion, D. Live IUGR', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Robe sign - the presence of a gas shadow within the hea or the greater vessels, seen in cases of fetal death in utero.It is a rare sign caused by postmoem blood degeneration, usually seen 1-2 days after death; and may be seen as early as 12 hours(Ref: Diagnostic Ultrasound by Carol M. Rumack, Stephanie R. Wilson, J. William Charboneau, and Deborah Levine,4thed, page 1090)', 'role': 'assistant'}]