<prompt> Among the following, the most sensitive antenatal USG finding of Trisomy 21 is:Absent nasal boneThickened nuchal foldSho femurEchogenic bowel  <response>: Prenatal USG markers of Down syndrome- Thickness of nuchal fold 75 sensitive Absence of nasal bone 58 sensitive cardiac abnormalities, duodenal atresia, shoened femur, shoened humerus, echogenic bowel 