Final answer:
The true statement about a nerve is that it can contain both sensory and motor nerve fibers, as nerves in the PNS, including spinal nerves, are typically mixed nerves carrying both types of axons.
Step-by-step explanation:
Which statement is true regarding a nerve? The correct answer to this question is b. A nerve can contain sensory (afferent) and motor (efferent) nerve fibers (axons). This is because nerves are cable-like structures that consist of bundles of axons, which carry information to and from the central nervous system. In the peripheral nervous system (PNS), nerves are classified as sensory, motor, or mixed based on the direction in which they carry nerve impulses. Spinal nerves and many cranial nerves are examples of mixed nerves, as they contain both sensory axons, which transmit information from sensory receptors to the central nervous system, and motor axons, which convey impulses from the central nervous system to effectors like muscles or glands. These nerves are surrounded by protective coverings: the outermost layer is the epineurium, groups of axons (fascicles) are wrapped in perineurium, and each individual axon is ensheathed in endoneurium, which is not an outer protective covering but a delicate layer of connective tissue within the nerve.