Explanation:

- Yuan Shikai – Correct Answer: He was the first official President of the Republic of China, serving from 1912 to 1915. Yuan played a significant role during the transition from the Qing Dynasty to the establishment of the republic.

- Hu Jintao – He was the President of the People's Republic of China from 2003 to 2013. This is a different entity from the Republic of China, which refers to the government established after the fall of the Qing Dynasty.

- Li Xiannian – He was a Chinese politician who served as the President of the People's Republic of China from 1983 to 1988, not the Republic of China.

- Yang Sangkun – He was President of the People's Republic of China from 1988 to 1993, so not related to the Republic of China's early history.