This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'patient with atrial fibrillation which is false : \nSelect and explain. \nA. Brain imaging is not done, B. trop i/t sent, C. echo done, D. all', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ref : harissons 21st ed', 'role': 'assistant'}]