Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: A motor neuron and all the muscle fibers that it innervates constitute: 
 Options:  <1> Motor plate. <2> Motor unit <3> Neuromuscular junction <4> Motor synapse <5> Motor filament
