Which bone forms the side of the head by the ear?

The temporal bone is the correct answer because it is located on the sides of the skull, specifically forming a part of the lateral aspect, around the area of the ear. It plays a critical role in surrounding and protecting the structures of the inner ear and is involved in the formation of the skull.

In anatomical terms, the temporal bone houses important components such as the auditory structures and is also where the mandible (jawbone) connects to the skull at the temporal bone's mandibular fossa. This connection is crucial for jaw movements, which are fundamental to functions like speaking and eating.

The other bones mentioned serve different functions and are located in distinct areas of the skull. The occipital bone is situated at the back of the skull and is primarily responsible for protecting the brain and forming the base of the skull. The ethmoid bone is located between the eyes and contributes to the eye sockets and nasal cavities, while the zygomatic bone, or cheekbone, forms the prominence of the cheeks but does not have a direct association with the area by the ear. Recognizing the specific functions and locations of these bones clarifies why the temporal bone is distinctly related to the sides of the head near the ear.