Which major event occurred on September 11, 2001?

The major event that occurred on September 11, 2001, was the terrorist attacks on the United States. On that day, coordinated attacks were carried out by the extremist group al-Qaeda, which included the hijacking of four commercial airplanes. Two of these planes were flown into the Twin Towers of the World Trade Center in New York City, leading to their collapse, while another plane targeted the Pentagon, and the fourth, Flight 93, was redirected by passengers and ultimately crashed in Pennsylvania. This tragic event resulted in significant loss of life and had a profound impact on U.S. foreign and domestic policy, including heightened national security measures and the initiation of the War on Terror.

The other options do not accurately represent the major historical event of that day. An economic recession refers to a significant decline in economic activity, which is not specific to that date; the moon landing took place in 1969; and while there have been presidential assassinations in U.S. history, none occurred on September 11, 2001.