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': 'The most sensitive test for the diagnosis of myasthenia gravis is - \nSelect and explain. \nA. Elevated serum ACH-receptor binding antibodies, B. Repetitive nerve stimulation test, C. Positive edrophonium test, D. Measurement of jitter by single fibre electromyography', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]