Which cranial nerves are classified as pure motor?

Cranial nerves that are classified as pure motor primarily serve to innervate muscles and are responsible for motor functions without sensory components. The correct choice includes cranial nerves III (oculomotor), IV (trochlear), and VI (abducens), which are all purely motor nerves.

The oculomotor nerve controls most of the eye's movements, including the constriction of the pupil and maintaining an open eyelid. The trochlear nerve innervates the superior oblique muscle, which is involved in downward and inward eye movements. The abducens nerve controls the lateral rectus muscle, responsible for moving the eye laterally.

Thus, these three nerves are exclusively motor in function and do not have sensory fibers associated with them, making this option the right selection for pure motor cranial nerves.