The statement that accurately compares the social structures of Egypt and Mesopotamia is: "Priests and priestess were closer to the pharaoh in ancient Egypt."
In ancient Egypt, priests held significant power and influence, often working closely with the pharaoh and serving important religious functions. In contrast, while Mesopotamian priests were also important, they did not typically wield the same level of authority or direct connection to the king as in Egypt.
The other statements about merchants, enslaved people, and scribes do not accurately reflect the social hierarchies of these civilizations.