Test analysis: This question mainly examines the students' ability to accurately interpret the information in the material. The words in the materials show that before Emperor Xiaowen's reform in the Northern Wei Dynasty, farmers were forced to migrate as refugees. In order to change this situation, the Northern Wei regime implemented the system of equal land in economy, ensured the farmers' land to be cultivated, and reorganized the bureaucracy in politics, which was beneficial to social stability, so it chose B.