The original Mesopotamian writing system first came from a system of clay tokens used to count agricultural goods. By the end of the 4th century BC, this had transformed into a method of keeping accounts, using imprints of a wedge-shaped tool. At first, it was used only for numbers, then finally for a general writing system.

Which of these is described by the passage above?
A.
hieroglyphics
B.
oral tradition
C.
Roman script
D.
cuneiform