Which of the following best describes the nervous system?

The nervous system is best described as the body's communication network made up of nerve cells. This definition captures the fundamental role of the nervous system in transmitting signals between different parts of the body and coordinating responses to internal and external stimuli. Nerve cells, or neurons, are specialized to send and receive messages through electrical and chemical pathways, enabling fast communication throughout the body.

The other options do not accurately encompass the entirety of the nervous system's function and structure. While the nervous system does interact with muscles and glands, focusing solely on these elements misses the broader aspect of communication that defines the system. Reflex pathways are a part of the nervous system's function, but they do not represent the full extent of its role in information processing and coordination. Additionally, hormonal control is primarily the function of the endocrine system, which operates separately from the nervous system, even though there can be interactions between the two systems through the neuroendocrine axis. Thus, option B provides the most comprehensive and accurate description of the nervous system as a whole.