The US President who visited China in 1972, was:

Richard Nixon

The correct answer is option (2) - Richard Nixon

1972: US President Richard Nixon’s visit to China
Henry Kissinger, an advisor to US President Richard Nixon, undertook a confidential trip to China via Pakistan in July 1971.
After him US President Richard Nixon visited China. From February 21 to 28, 1972, President Richard Nixon traveled to Beijing, Hangzhou, and Shanghai.