Final answer:
The temporal bones (option A) form the inferior portion of the sides and base of the cranium, contributing to the structure of the skull and protection of the brain.
Step-by-step explanation:
The inferior portion of the sides and base of the cranium is comprised of the temporal bones. These bones form the lower lateral side of the skull and are involved in the formation of the temple region where hair traditionally starts to show signs of aging. The temporal bones are bounded by other bones of the cranium, including the paired parietal bones, the occipital bone, and the sphenoid bone. They play a critical role in protecting the brain and supporting the structures of the head.