B. Defeating the Nationalists in a violent civil war.
Explanation:
The Chinese Civil War was a war fought between the Kuomintang government of the Republic of China and the Communist Party of China. The final phase of this was known as the Chinese Communist Revolution, and it resulted in the rise to power of the Communist Party of China. After the war, the Nationalist government (Kuomintang) retreated to the island of Taiwan, with both parties claiming to be the "legitimate" government of all of China.
