a. spinal cord
Spinal Cord is the part of the nervous system responsible for connecting the brain to the body.
The nervous system is divided into two groups. The Central Nervous System and the Peripheral Nervous System.
The Central Nervous System involves the Brain and the Spinal Cord. Its contains the integrative and control centers.
The Peripheral Nervous System involves the cranial nerves and spinal nerves. It is composed of the communication lines between the Central Nervous System and the rest of the body.