2 things:

1) if there was an embolus in any of the other arteries, there would be more severe symptoms outside of the vision loss

2) Ophthalmic artery (a branch of the internal carotid artery) also supplies the retinal artery and blood to the eye most directly

All arteries of the other options besides the right ophthalmic are anatomically separated from the arterial supply to the right eye. It is impossible for them to send cholesterol emboli to the right eye.

It is confusing because a thrombus from the deep veins of the lower limbs can embolize CNS arteries if the patient has a patent foramen ovale - paradoxical embolism.