Final answer:
The persistent vegetative state is characterized by preserved eye opening and preserved sleep-wake cycles but not by preserved eye tracking, which requires conscious perception and voluntary motor response.
Step-by-step explanation:
The persistent vegetative state (PVS) is a condition in which a person loses the higher cerebral powers of the brain, but retains basic brain function. This condition is characterized by several features. A correct statement regarding PVS is that it involves preserved eye opening and preserved sleep-wake cycles, meaning patients can open their eyes and may appear to be awake at times. However, PVS is not typically associated with a preserved response to noxious stimuli, meaning the patient does not have a purposeful response to pain. PVS patients also do not exhibit preserved swallowing or preserved eye tracking, which are both complex actions requiring higher brain function.
Given the options provided, preserved eye tracking is not a characteristic of PVS, as eye tracking requires the conscious perception of visual stimuli and voluntary motor response, which are typically lost in this state.