Answer:The correct order is:
Ion channels - synaptic vesicle - neurotransmitter - end plate potential.
Explanation: A neuromuscular junction is the point where a motor neuron meets with a skeletal muscle fiber which it innervates.
It is the site where a chemical interaction or communication between a motor neuron and a muscle cell occurs. For transmission of impulses to occur between a neuron and a muscle cell, an action potential from the motor neuron travels along the axon of the neuron to the presynaptic terminal of the neuron where it activates voltage gated calcium ion channels which causes the influx of calcium ions into the intracellular space of the neuron. The calcium ions bind to the sensor proteins that are located on the synaptic vesicles and trigger the release of the neurotransmitter into the synaptic cleft. The neurotransmitter moves from the synaptic cleft and binds to its receptors on the postsynaptic membrane of the muscle cell. The binding of the neurotransmitter to its receptors creates end plate potential which causes the skeletal muscle fibers to depolarise.