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: Radiology
[{'content': "USG can diagnose all except: \nSelect and explain. \nA. Anencephaly, B. Neural tube defect, C. Placenta pre, D. Down's syndrome", 'role': 'user'}, {'content': "Answer: D \nExplanation: D i.e. Down's Syndrome In anencephaly, absece of vault. In NTD, presence of meningo-myelocoel & In placenta pre location of placenta seen by USG confirms the diagnosis. Although on prenatal U/S increased nuchal fold thickness, and reduced length of femur & humerus are suggestive of Down's syndrome but the diagnosis is confirmed by chromosomal study (trisomy of 21st autosome) either by amniocentesis or chronic villous sampling.", 'role': 'assistant'}]