The correct contribution of the Mesopotamians to the evolution of writing is:
B. They developed a system script known as cuneiform, which involved making marks on clay tablets.
Cuneiform is one of the earliest known systems of writing, which originated in ancient Mesopotamia around 3400 BCE. It was used for various languages spoken in the region, including Sumerian and Akkadian. Cuneiform involved making wedge-shaped marks on clay tablets with a stylus.