In the sciatic nerve - sartorius experiments, the fatigue of muscle contraction after successive stimulation of nerve fiber is caused by
A、the inhibition of the signal transmission at neuro-muscle junction.
B、the decrease of the action potential amplitude.
C、the decreae of the speed action potential propagates on the nerve fiber.
D、the low excitability of the muscle.
E、the decreased efficiency of the signal transmission at triad of the sarcolemma.