Final answer:
A deficiency in Vitamin A can lead to aural abscesses in captive terrestrial box turtles, as it is essential for maintaining healthy skin, mucous membranes, and immune system functions.
Step-by-step explanation:
Deficiencies in certain vitamins can lead to various health issues in animals, including captive terrestrial box turtles. When it comes to aural abscesses in box turtles, a deficiency in Vitamin A is often the culprit. This condition can manifest as swelling behind the ear due to the buildup of pus. Vitamin A is essential for proper functioning of the skin, mucous membranes, and immune system, among other biological processes. Thus, maintaining adequate levels of this vitamin is crucial for turtle health. On a related note, Vitamin C is a water-soluble vitamin, unlike Vitamin A which is fat-soluble.