Even more demanding in artistic technique were the small cylinder seals used to roll one's signature into the wet clay of a tablet recording a commercial transaction.
Which of the sentence below best express the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. The artistic technique then was difficult because they have to roll their signature into the wet clay of a tablet to record a commercial transaction.
B. One artistic technique was to use small cylinder seals to record a commercial transaction.
C. They used small cylinder seals to roll their signatures into a tablet to record a commercial transaction, which was a very difficult technique then.
D. It required high degree of skill to make small cylinder seals because it was difficult to roll one's signature into the wet clay of a tablet.
