The correct answer is - B. Their hair and skin color.
The hair and skin color of the hominids is not related to the shape and size, or rather the anatomy of the skull. The development of hair and skin color is actually dependent on the surrounding environment, since it can be used for camouflage, for protection of cold, or protection of the sun, but it has nothing to do with the bone structure of the skull.
The anatomy of the skull is defined by the eating habits, the way of motion, the size and the shape of the brain.
