What Ensures That One Action Potential in the Neuron Yields

Multiple Choice

What ensures that one action potential in the neuron yields only one action potential in the skeletal muscle fibers of the stimulated motor unit and therefore only one contraction per fiber?

A) the amount of calcium that enters the pre-synaptic cell
B) the rate of diffusion of acetylcholine across the synaptic cleft
C) the number of muscle fibers that make up the motor unit
D) enzymatic breakdown of acetylcholine by acetylcholinesterase
E) All of these ensure this one to one ratio.