Why Was Chinese Writing Referred to as the Key to the Creation

Why was Chinese writing referred to as the key to the creation of a distinctive Chinese identity?

A) The Chinese were the only civilization to evolve their writing system from pictographs.
B) The Chinese were the only civilization to utilize their writing for commerce.
C) The Chinese writing system encouraged almost universal literacy among Chinese people.
D) The written language served to unite the various ethnic groups who were able to identify themselves through writing as culturally Chinese.