Textual research and analysis: "Li Yuanyuan citizens were exempted from the Warring States period", that is, the people of CoCo Lee got rid of the situation of warlord separatism and melee during the Warring States period and began to have a relatively stable production environment. This shows that Qin Shihuang's great historical achievement is to eliminate the six eastern countries and complete the reunification of the country. So choose a.

Comments: From the demise of Korea in 230 BC to the demise of Qi in 22 1 BC, Qin completed the unification of the six countries in the first ten years. From then on, it ended the feudal separatist situation since the Spring and Autumn Period and the Warring States Period, and established the first unified multi-ethnic centralized feudal country. The Qin Dynasty carried out many measures to eliminate separatist factors, which laid the foundation for the long-term reunification of China. This has had a great and far-reaching impact on the development of China's history.