Answer:
Correct answer is Option 1. muscle fibers that the branches contact.
Explanation:
A motor unit is made up a motor neuron also known as an axon and the number of muscle fibers that the branches have contact with.
Motor units function in such a way that they organise the contractions of one muscle when they receive a signal from the brain.
Motor units can come in
a. Large sizes : an example is the muscle in the limbs
b. Small sizes: an examples is the muscle in the eyes
