The correct answer is: The clay bricks and mud the Sumerians used as building materials were not very durable.
Sumerian art, which included pottery, sculptures, and architectural structures, was primarily made from materials like clay and mud, which are more susceptible to erosion and decay over time compared to the stone used by the ancient Egyptians. This is why we have less surviving art from the Sumerian culture compared to that of the Egyptians.