Which of the following parts of a neuron is covered by a fatty sheath?

Axon.

The correct answer is Option (1) - Axon.

The axon is a long fibre, the distal end of which is branched. Each branch terminates as a bulb-like structure called synaptic knob which possess synaptic vesicles containing chemicals called neurotransmitters. The axons transmit nerve impulses away from the cell body to a synapse or to a neuro-muscular junction.

There are two types of axons, namely,myelinated and non-myelinated.

The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon.  Myelinated nerve fibres are found in spinal and cranial nerves.

Unmyelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon, and is commonly found in autonomous and the somatic neural systems.

Cyton is the metabolic center of the nerve cell where the metabolic contents are manufactured.

Dendrites are the small extension of nerve cells that receives signals from sensory receptors or other neurons.

Dendrites and cyton are not involved in nerve impulse conduction.

The gaps between two adjacent myelin sheaths are called nodes of Ranvier.