Which of the following is the correct airport code for the city of Greensboro, North Carolina?

The correct airport code for Greensboro, North Carolina, is GSO. This code refers specifically to Piedmont Triad International Airport, which is the primary airport serving the Greensboro area. Each airport code is unique and typically reflects either the city or the airport's name, and GSO is derived from the initials of the city name, Greensboro, with "O" representing the airport itself.

To provide context, GSP is the airport code for Greenville-Spartanburg International Airport, which is located in South Carolina and serves a different region. GDL represents Miguel Hidalgo y Costilla Guadalajara International Airport in Mexico, while HNL is the code for Daniel K. Inouye International Airport in Honolulu, Hawaii. These codes each correspond to airports that are unrelated to the Greensboro area, further emphasizing why GSO is the correct choice for this question.