Final answer:
The ventral root is the structure that carries motor neurons out of the spinal cord, allowing them to reach and control skeletal muscles.
Step-by-step explanation:
The structure in the nervous system that carries the motor neuron out of the spinal cord is the B) Ventral root. Motor neurons have cell bodies located in the ventral horn of the spinal cord.
These neurons project axons through the ventral root to reach the muscles. The spinal nerves then transmit both sensory and motor information between the spinal cord and the body. The ventral root specifically carries the motor outputs to the skeletal muscle.