Final answer:
The external occipital protuberance is the bony landmark on the occiput that serves as an attachment site for several neck muscles.
Step-by-step explanation:
The bony landmark of the occiput that serves as an attachment site for several neck muscles is the external occipital protuberance. The mastoid process, while also a part of the skull, is located in the mastoid portion of the temporal bone and is not a part of the occiput. It too serves as a muscle attachment site but it's more posterior and can be felt behind the earlobe. The styloid process, on the other hand, is an elongated, downward bony projection located on the external base of the skull that serves as an attachment site for several small muscles and for a ligament that supports the hyoid bone of the neck.