Su Shi praised Yan Gong, a great calligrapher of the Tang Dynasty, for his new ideas and his fine tendons that penetrated into his bones like an autumn eagle. Who was Su Shi's calligrapher?

"Yan Gong's reforms brought out new ideas, and his muscles were as thin as an autumn eagle." The calligrapher Su Shi praised was Yan Zhenqing of the Tang Dynasty. After Wang Xizhi, the most accomplished calligrapher in the history of Chinese calligraphy was Yan Zhenqing of the Tang Dynasty. He created his own "Yan style". His regular script structure is square and dense, with light horizontal strokes and heavy vertical strokes, strong and round strokes, and solemn and powerful momentum.

Therefore choose B.