This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Radiology
[{'content': 'The earliest sign of uteroplacental insufficiency on Doppler is? \nSelect and explain. \nA. Diastolic notch, B. Reversal of diastolic flow, C. Blunting of systolic flow, D. Absent mid diastolic flow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans AThe signs of uteroplacental insufficiency in increasing order of severity are early/pre diastolic notch, absent diastolic flow and lastly reversal of flow during diastole.', 'role': 'assistant'}]