Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

• Sumerian script, the earliest known form of writing among prehistoric writing systems, was first used on clay tablets for accounting purposes.
• Although the earliest Sumerians engaged in commercial activity and practiced accounting, they were not as literate as people in other parts of the prehistoric world.
• Archaeologists have discovered that literacy was developed in several parts of the world, including ancient Mesopotamia.
• Archaeological detective work has revealed the commercial accounting practices of the Sumerians of ancient Mesopotamia and provided a written record of their intense commercial activity.

This is a multiple choice.