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': 'Which test is not useful in a patient with history of syncopal attack - \nSelect and explain. \nA. Electrophyciological test, B. Table tilt test, C. PET scan, D. Holier monitoring', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]