This topic examines current events. 1972 February 2 1 February 28, US President Nixon paid an official visit to China. On February 28th, China and the United States issued the Sino-US Joint Communiqué, the Shanghai Communiqué, which guided the relations between the two countries, and the door of Sino-US exchanges finally opened. Nixon's successful visit to China and the publication of the Shanghai Communique is an important page in the history of Sino-US relations, which marks the beginning of the normalization process of Sino-US relations after more than 20 years of confrontation and lays the foundation for the further improvement and development of Sino-US relations in the future. Therefore, the correct answer to this question is A.