How Does an Impulse from a Motor Neuron Trigger a Muscle

Multiple Choice

How does an impulse from a motor neuron trigger a muscle cell to contract?

A) Acetylcholine is released from the neuron, triggering calcium release from the muscle cell's endoplasmic reticulum
B) Acetylcholine is released from the neuron, triggering calcium absorption by the muscle cell's endoplasmic reticulum
C) Acetylcholine is released from the muscle cell, triggering calcium release from the neuron's endoplasmic reticulum
D) Acetylcholine is released from the neuron, triggering calcium to enter the muscle cell
E) Acetylcholine is released from the muscle cell, triggering calcium to enter the neuron