2.C

3.B

4.( 1) Sima Zhi is a native of Wenxian County, Hanoi.

(2) Sima Zhi sent a messenger to Jinan, the county seat, riding a fast horse. The letter listed Liu Jie's crimes in detail.

(3) Liu Xun wrote an unsigned letter to Sima Zhi, but he repeatedly asked Sima Zhi for help in the letter. Sima Zhi didn't reply to his letter, and the matter was handled according to law.