Ping-Pong diplomacy took place between the United States and China.
1. Ping-Pong diplomacy refers to a series of table tennis (Ping-Pong) exchanges between the United States and China in the early 1970s.
2. It was a significant event that helped improve diplomatic relations between the two countries, which had been estranged since the Chinese Civil War in the late 1940s.
3. This sports diplomacy led to the visit of the Chinese table tennis team to the United States in 1972 and paved the way for U.S. President Richard Nixon's historic visit to China in 1972, marking the beginning of normalized relations between the two nations.
Therefore, the correct completion for the sentence is: Ping-Pong diplomacy took place between the United States and China.
