Acetylcholinesterase: a) Is stored in vesicles in the motor neuron terminal b) Combines with receptors on the muscle membrane to depolarize the muscle cell/fiber c) Breaks down and inactivates acetylcholine d) Is the chemical transmitter at the neuromuscular junction e) Paralyzes skeletal muscle by binding to acetylcholine receptors

c) Breaks down and inactivates acetylcholine

Explanation:

Acetylcholinesterase is an enzyme that is required for termination of acetylcholine activity in the synaptic cleft. The enzyme is present in the extracellular side of the motor endplate membrane and breaks down the acetylcholine into acetyl and choline.

In the absence of acetylcholine, the muscle fibers resume their resting stage. Therefore, acetylcholinesterase activity is required for the normal functioning of muscles and nerve cells that use acetylcholine as a neurotransmitter.