First of all, the fragment is the Three Kingdoms period, and the characters were unified by Qin Shihuang after Qin unified China, so there was no unified characters at that time, excluding A; During the Three Kingdoms period, the font was mainly official script, and C obviously did not match; D not reflected in this topic. Chinese characters developed through Oracle Bone Inscriptions, inscriptions on bronze, big seal script and small seal script. Although it was perfected in later generations, D has nothing to do with the stem. The fragment shows the changes of characters in the Three Kingdoms from the pre-Qin period to that time. Choose B.