Concept:
Nervous tissue is specialized for receiving, processing, and transmitting impulses.
Step 1: Understanding nervous tissue.
Nervous tissue is made up of neurons and supporting cells called neuroglia.
Step 2: Role of neuron.
A neuron is the structural and functional unit of the nervous system. It receives stimulus and conducts nerve impulses.
Step 3: Parts of neuron.
A neuron has:
• Cell body
• Dendrites
• Axon
Step 4: Checking other options.
Nephron is the functional unit of kidney.
Osteon is the structural unit of compact bone.
Sarcomere is the functional unit of muscle contraction.
Neuron is the functional unit of nervous tissue.
\[
\boxed{\text{Neuron}}
\]