This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ULTRASOUND, Subject name: Radiology
[{'content': 'All are true about antenatal umbilical aery Doppler except? \nSelect and explain. \nA. Decreased diastolic flow of umbilical aery is suggestive of IUGR, B. S/D Ratio of umbilical aery is less than S/D ratio of Fetal MCA, C. S/D Ratio is decreased in smoking females, D. Reversal of diastolic flow in umbilical aery Doppler suggests impending Fetal demise', 'role': 'user'}, {'content': 'Answer: C \nExplanation: S/D Ratio of umbilical aery Doppler is increased in smokers. Decreased, absent or reversal of diastolic flow on umbilical aery Doppler suggests fetal IUGR and impending Fetal death. Fetal MCA S/D ratio is normally more than S/D ratio of umbilical aery. Fetal MCA S/D ratio is less than S/D ratio of umbilical aery Doppler in IUGR.', 'role': 'assistant'}]