The vascular supply associated with contralateral visual field deficits and altered mentation is:

The correct answer focuses on the posterior cerebral artery (PCA) because it primarily supplies the occipital lobe and inferior part of the temporal lobe, areas that are crucial for visual processing. In the case of a PCA infarct, a patient may experience contralateral visual field deficits, such as homonymous hemianopsia, which is a loss of half of the visual field in both eyes opposite to the side of the infarct.

Moreover, PCA ischemia can lead to altered mentation due to its proximity to structures in the brain responsible for cognitive function and visual processing. Patients might also exhibit difficulty with visual recognition or other cognitive functions associated with the temporal lobe depending on the extent of the ischemic damage. The connection between the posterior cerebral artery and visual deficits, along with cognitive changes, makes this option the most appropriate choice in the context of the question.

The other vascular supplies listed do not directly correlate with the specific symptoms presented. For example, the middle cerebral artery focuses more on areas responsible for motor and sensory functions, and the anterior cerebral artery primarily supports motor and sensory areas for the lower body and has less impact on visual processing. The vertebrobasilar arteries primarily supply the brainstem and cerebellum,