This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, 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: *Tensilon (edrophonium) test: a sho-acting anticholinesterase--look for rapid and transient improvement of strength; false-positive (placebo response, motor neuron disease) and false-negative tests occur. Atropine IV should be on hand if symptoms such as bradycardia occur. Ref Harrison20th edition pg 2378', 'role': 'assistant'}]