Analysis of test questions: China Tang Dynasty calligrapher. An outstanding calligrapher in the middle Tang Dynasty. His "Yan Ti" regular script, together with Zhao Mengfu, Liu Gongquan and Ou Yangxun, is also called "the four masters of regular script"; Liu Gongquan's calligraphy is famous for regular script, which is as famous as Yan Zhenqing, and is called Yan Liu. Wang Xizhi, a beginner of his calligraphy; Zhang Xu was a calligrapher in Tang Dynasty, and cursive script was his representative. Option a meets the question.
Comments: The difficulty of this question is moderate, and the key to the analysis is that students need to understand their respective achievements.