Answer:
A motor unit is a group of MOTOR NEURON and the MUSCLE FIBERS connected to it.
Explanation:
Neuron is the structural and functional unit of nervous system.
Motor unit consists of a motor neuron and the skeletal muscles innervated by the terminals of the neuron.
Several associated motor units called motor pool coordinates together the contractions of a single muscle.
That is, the activation of a motor unit leads to the contraction of all the muscle fibers attached to it.