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: Surgery
[{'content': 'Which of the following is false about ambulatory pH monitoring \nSelect and explain. \nA. H2 blocking agents must be stopped before 3 days, B. PPI must be stopped before 14 days, C. Sensitivity and specificity is 70%, D. It is done before antireflux surgery', 'role': 'user'}, {'content': 'Answer: C \nExplanation: It has a sensitivity and specificity of 92%', 'role': 'assistant'}]