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
The most sensitive test for the diagnosis of ' myasthenia gravis is 
Select and explain. 
A. Elevated serum ACH-receptor binding antibodies, B. Repetitive nerve Stimulation test, C. Positive edrophonium test, D. Measurement of jitter by Single fibre electromyography
C: Positive edrophonium test
Answer: C: Positive edrophonium test 
Explanation: *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