A ganglion is which of the following?

A ganglion is best defined as the sensory nerve cell bodies in the posterior root. In the context of the nervous system, a ganglion is a cluster of neuronal cell bodies located in the peripheral nervous system, and the posterior root ganglion specifically contains the cell bodies of sensory neurons that transmit information from the body's periphery to the central nervous system. This distinction is vital for understanding how sensory information is processed, as these ganglia serve as relay points for sensory signals before they reach the spinal cord.

Other options do not fully capture the definition of a ganglion. While a type of nerve cell exists, the term "ganglion" refers to a grouping of these cells rather than an individual one. Additionally, although part of the gray matter of the spine does involve nerve cell bodies, this is not synonymous with a ganglion, which is found outside the central nervous system. Similarly, while there are collections of nerve endings, a ganglion specifically pertains to the clustering of the cell bodies of neurons, which distinguishes it from mere endings of nerve fibers.