In the absence of extracellular Ca++, an action potential in a motor neuron failed to initiate contraction of the innervated skeletal muscle because of:
A. inhibition of Ca++ influx into the innervated muscle
B. inhibition of ACh binding to receptors on the muscle end plate
C. stimulation of ACh degradation
D. inhibition of ACh release from the motor neuron
E. inhibition of Ca++ binding to troponin C in the innervated muscle
ANS: D
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