Final answer:
Cream-colored horses must have the colors Bay and Black in their genetic lineage.
Step-by-step explanation:
In the genetic lineage of a cream-colored horse, the colors that must be present are Bay and Black.
In the given information, a. Gray body and cinnabar eyes are dominant, and d. Gray body and red eyes are dominant. This means that a cream-colored horse must have a gray body. However, it does not specify which eye color is associated with a cream-colored horse.
Therefore, the color of the horse can be either Bay (brown body with black mane and tail) or Black (black body with black mane and tail).