Final answer:
The sagittal suture divides the right and left parietal bones at the top of the skull. The correct option is D.
Step-by-step explanation:
The sagittal suture is the joint that unites the right and left parietal bones at the midline along the top of the skull. This suture is distinct from others such as the coronal suture, which joins the parietal bones to the frontal bone, and the lambdoid suture, which joins the parietal bones to the occipital bone.
Specifically, the sagittal suture extends posteriorly from the coronal suture and terminates by joining the lambdoid suture. Therefore, the bones that are divided by the sagittal suture are the right and left parietal bones.