What are nerves primarily made up of?

Nerves are primarily made up of bundled axons. Axons are long, slender projections of neurons that transmit electrical impulses away from the neuron's cell body. When many axons group together, they form a nerve, which serves as a communication pathway for signals between different parts of the body and the central nervous system.

The other components mentioned in the options—such as neurons, neurotransmitters, dendrites, synapses, myelin, and synaptic vesicles—play important roles in the overall functioning of the nervous system. However, they do not define the structural composition of a nerve itself. For example, while neurotransmitters facilitate communication between neurons at the synapse, they do not make up the physical structure of a nerve. Similarly, myelin is a fatty substance that covers many axons to increase signal transmission speed, but it is not a component that defines the entirety of a nerve structure. Therefore, recognizing that nerves are fundamentally formed from bundled axons is essential to understanding their role in the nervous system.