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: Medicine
[{'content': 'Doppler ultrasound, all are true except? \nSelect and explain. \nA. Monophasic tracing measure normal flow, B. Provide information about blood velocity, C. Direction of blood flow,, D. Degree of stenosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]