Answer:
The correct answer to this question: If you were to sit on a horse´s back you would be on the ____ aspect of the bone, would be: D: Dorsal.
Explanation:
Given my research this question does not refer to the aspect of the bone itself, but rather, the positional reference of the bones with regards to the part of the horse where you are sitting. Thus, the full question found ends with; ___ aspect of the horse, not the bone. This has to do with how we term the position of bones, and other structures, relative to one another, ventral, inferior or anterior, posterior and dorsal. But because we are talking about a human bone´s position in relation to the body of an animal, like the horse, then we would say that the position of our sitting bone, relative to the horse, would be dorsal.