World’s busiest airports by passenger traffic is

Hartsfield-Jackson Atlanta International Airport, USA
Lhasa Airport, Tibet
King Abdul Aziz International Airport, Saudi Arabia
Chicago O' Hare International Airport, USA

The correct answer is A. Hartsfield-Jackson Atlanta International Airport, USA.

Hartsfield-Jackson Atlanta International Airport is the busiest airport in the world by passenger traffic, handling over 110 million passengers in 2021. It is located in Atlanta, Georgia, and is the hub for Delta Air Lines. The airport has six concourses and 200 gates, and is served by over 100 airlines.

Lhasa Airport is the second busiest airport in Tibet, after Gonggar Airport. It is located in Lhasa, the capital of Tibet, and is the main gateway to the region. The airport has one runway and one terminal, and is served by Air China, China Eastern Airlines, China Southern Airlines, and Tibet Airlines.

King Abdul Aziz International Airport is the largest airport in Saudi Arabia and the sixth busiest airport in the world by passenger traffic. It is located in Jeddah, on the Red Sea coast of Saudi Arabia. The airport has two terminals and five runways, and is served by over 90 airlines.

Chicago O’Hare International Airport is the second busiest airport in the United States, after Hartsfield-Jackson Atlanta International Airport. It is located in Chicago, Illinois, and is the hub for United Airlines. The airport has six concourses and 191 gates, and is served by over 70 airlines.