Which one of the following is not a part of nerves ?

Which one of the following is not a part of nerves ?

Axons
Connective tissues
Schwann cells
Smooth muscles
This question was previously asked in
UPSC NDA-1 – 2015
Nerves are bundles of nerve fibers (axons) covered by protective sheaths and supported by connective tissue.
Axons are the main projections of nerve cells that transmit signals. Schwann cells (a type of glial cell) form the myelin sheath around axons in the peripheral nervous system. Connective tissues (epineurium, perineurium, endoneurium) form the outer layers and internal support structure of nerves. Smooth muscles are a type of muscle tissue found in organs and blood vessels; they are not structural components of a nerve. While nerves innervate smooth muscles (control their function), the muscle tissue itself is not part of the nerve structure.
The basic structural unit of a nerve is the neuron, which includes an axon. Axons are bundled together to form nerves. Glial cells like Schwann cells provide support and insulation. Connective tissue provides structure and protection to the nerve bundle.