Final answer:
The classification of a nerve that carries autonomic signals away from the CNS is a visceral efferent nerve.
Step-by-step explanation:
The student's question pertains to a nerve that carries autonomic signals away from the central nervous system (CNS). From the provided options, the correct classification is a visceral efferent nerve. The word efferent indicates that the nerve fibers are carrying signals away from the CNS towards the effectors, and visceral specifies that these signals control the function of internal organs as part of the autonomic nervous system - which operates involuntarily.
Motor neurons (efferent neurons) are responsible for transmitting information from the CNS to the muscles and glands, and are therefore part of the efferent pathways. Whereas, sensory neurons (afferent neurons) carry impulses from sensory receptors towards the CNS, making up the afferent pathways. Since the question specifically mentions autonomic (visceral) and not somatic (voluntary muscle control), this eliminates the options pertaining to the somatic nervous system.
Therefore, the answer to the student's question is (C) visceral efferent.