The correct answer is B) Nixon's diplomatic mission to China caused a release in political tension among the two countries.
President Nixon's visit to China in 1972 marked a significant turning point in U.S.-China relations, as it opened up diplomatic communication and initiated a period of engagement between the two countries. This diplomatic mission helped to reduce tensions that had existed since the Chinese Communist Revolution in 1949 and ultimately led to the normalization of relations between the U.S. and China. The visit is often seen as a strategic move to counter Soviet influence during the Cold War as well.