Answer:
The best description for why the author used the following comparison - "One of his eyes resembled that of a vulture" - is a simile used to connect the eye to something associated with death - The Vulture. The comparison is meant to convey the physical appearance of the eye, which is likely gaunt and sharp like that of a vulture, a bird known for scavenging on dead animals. The simile also helps to create a vivid and memorable image for the reader, enhancing the overall effect of the description.