Final answer:
The optic nerve (cranial nerve II) is classified as sensory, transmitting visual data from the retina to the brain without any motor or preganglionic parasympathetic fibers.
Step-by-step explanation:
Cranial nerves are categorized based on their function as sensory, motor, or mixed. The optic nerve, also known as CN II, is one of the 12 cranial nerves in humans and is dedicated strictly to transmitting sensory information, specifically visual data, from the retina of the eye to the brain. It is devoid of motor fibers or any preganglionic parasympathetic fibers. As part of the central nervous system, the optic nerve is responsible for the sense of sight and connects directly to the brain.
Unlike spinal nerves, which are mixed and contain both sensory and motor fibers, cranial nerves can have highly specialized roles. In the mnemonic "Some Say Marry Money But My Brother Says Brains Beauty Matter More," the 'S' in "Say" helps to remember that CN II is sensory.