Choose the correct answer:

The Sumerian system of writing

is the answer because cuneiform was the Written language of Sumerians which can be traced back to 8000 BC. This early writing consisted of making specific marks in wet clay with a reed implement.

a) is not the answer because pictograph is a pictorial symbol for a word or phrase. They were used as the first known form of writing. They were discovered from Egypt and Mesopotamia from before 3000 BC.

b) is not the answer because hieroglyphic (Greek for "sacred writing") was a character of the ancient Egyptian writing system. Logographic scripts that are pictorial in the form in a way significant of very old Egyptian are also sometimes called "hieroglyphs".

c) is not the answer because sonogram is a medical examination of scanning the human body. It is an ultrasound exam that uses high-frequency sound waves to scan a woman's abdomen and pelvic cavity, making a picture (sonogram) of the baby and placenta.