Correct answer:
A. establishing full diplomatic relations.
Historical context / explanation:
On December 15, 1978, after months of secret talks, the United States and the People’s Republic of China announced that they would recognize each other and establish official diplomatic relations with one another, effective January 1, 1979. In doing so, the United States also acknowledged the government of the People’s Republic of China as the legal government of China, and withdrew its support for the claim that Taiwan (the Republic of China) had continued to make about its legitimacy over against the communist government that had been in place in mainland China since 1949.
